#20 Daley Blind | Manchester United to Ajax | £14m
He left Ajax for Manchester United as a four-time Eredivisie champion and returns four years later with Europa League, FA Cup and Carabao Cup winners' medals added to his collection. Ajax, meanwhile, have won nothing since his departure and are desperate to put an end to that dry spell this season.
The 28-year-old looks more refined and commanding at centre-back and will prove a great partner for golden youngster Matthijs de Ligt while his experience is going ot be vital to their Champions League campaign.
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#19 Radja Nainggolan | Roma to Inter | £21m
"He is the turbine we were missing from our engine," Luciano Spalletti said of Inter's €24 million (£21m/$28m) signing from Roma.
The 30-year-old established himself as one of the best midfielders in Italy over his spells at Cagliari and Roma, but no longer felt important in the capital city.
The Belgium international still has a lot to offer, however, and he has reunited with a coach who knows exactly what to expect in ex-Roma boss Spalletti.
"He can do well. He has the character to go against any opponent," he added. "He is a ninja. He fights with everyone on any field."
#18 Stefan de Vrij | Lazio to Inter | Free
The Dutch defender has already emerged as a leader at Inter amid their poor start to the season.
De Vrij has already opened his account as he helped his team to a 2-2 draw against Torino, is a good ball-winner and has always been adept at distributing from defence.
After playing over 100 games for Lazio, he is already settled in Italy, making him a great free signing for the San Siro outfit.
#17 Fabinho | Monaco to Liverpool | £39m
The 24-year-old midfielder has been kept out of the Liverpool team so far by Georginio Wijnaldum, but coach Jurgen Klopp had warned that a gradual transition may be required despite Fabinho's £39 million ($52m) price tag.
"It is about players understanding the position and who else is available as well – otherwise Fabinho would have been involved in the squad, as he was in the first week," Klopp said.
"That is it. It is different football to what he is used to but he is improving already with big steps. I can see that in the sessions and that is cool.
“Fabinho is used to playing at a high level in France. It is not about who we play but about how we play. For sure it is not nice for a new player. It never was but it is all fine.”
Fabinho proved himself as a reliable and versatile midfielder over five years at Monaco, scoring 23 goals and setting up eight in 167 Ligue 1 appearances and will likely have a big say alongside Naby Keita when he makes his entrance.
#16 Moussa Dembele | Celtic to Lyon | £20m
Lyon jumped in at the last minute to steal Celtic's star forward before Marseille could get to him as they looked for a replacement for Mariano Diaz.
Celtic tried to hold off the French sides and reported interest from Borussia Dortmund, but the 22-year-old insisted on being sold before the window closed.
The striker may have soured relations with the club for whom he scored 51 goals in 94 games over two seasons, but the Glasgow side will rue the loss of a player who had previously been linked to several clubs from the Premier League and across Europe.
#15 Steven N'Zonzi | Sevilla to Roma | £27m
The 29-year-old reunited with old friend Monchi as the Roma sporting director orchestrated a €30 million (£27m/$34m) deal with Sevilla.
Arsenal and Barcelona had been chasing the midfielder who had long been regarded as one of the best in Spain after Monchi signed him the first time with Sevilla.
N'Zonzi went on to help France win the World Cup this year before heading to the Italian capital and has already secured his spot in the first team.
"Monchi helped me a great deal when I arrived at Sevilla," he said. "He's a top professional, who has shown he knows how to win. Now I just want to work hard and show everyone how good I am."
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#14 Lautaro Martinez | River Plate to Inter | £20m
The Argentine striker’s excellent goalscoring record at River Plate attracted interest from Real and Atletico Madrid, but it was Inter who nipped in to get him first in a €22.7 million (£20m/$26.4m) deal.
The 21-year-old’s excellent positioning and eye for a goal suggests he will prove a fruitful addition to the San Siro outfit and he looked impressive in pre-season, scoring a debut goal against Swiss side Lugano and the winner against Atletico.
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#13 Justin Kluivert | Ajax to Roma | £15m
The 19-year-old winger went against his father’s wishes and broke Ajax hearts when he announced he left for Roma after lambasting the Dutch club for their policy with young players.
The Serie A side snapped him up for just €17.25 million (£15m/$20m) and he made an immediate impact when he came on to set Edin Dzeko up for a late winner in the opening game against Torino.
A last-ditch tackle stopped him from having a decisive say in the 3-3 draw against Atalanta, but there will likely be many more bright moments for the potential superstar as he adapts to Eusebio Di Francesco’s side.
#12 Joao Moutinho | Monaco to Wolves | £5m
The 31-year-old joined Wolves for just £5 million after five years with Monaco and is already impressing the newly-promoted side’s fans.
Moutinho’s excellent cross set Willy Boly up for a crucial but controversial goal as they held Manchester City to a 1-1 draw recently, and he has looked sound in midfield for Nuno Espírito Santo’s team.
He is a Euro 2016 champion with Portugal, with whom he has 113 caps, and won Ligue 1 with Monaco - a real bargain for Wolves.
#11 Thomas Lemar | Monaco to Atletico Madrid | £53m
Atletico Madrid were the happy winners of the race to sign Liverpool and Arsenal target Thomas Lemar in a €60 million (£53m/$71m) deal form Monaco.
The most expensive signing by a Spanish club this summer, he is expected to add great firepower to a team consisting of Antoine Griezmann and Diego Costa.
"Lemar is a top player. A coach who has a player like Lemar is happy – he doesn't need to make substitutions to change formation," Monaco boss Leonardo Jardim said of the 22-year-old France international.
"Lemar understands football. He can play as a winger, an attacking or defensive midfielder or even a full-back. Central defender and striker are the only two positions he would struggle in."
#10 Jean Michael Seri | Nice to Fulham | £26.5m
Fulham pulled off a masterstroke in bringing Jean Michael Seri from Nice for around £26.5 million ($35m).
The 27-year-old came close to joining Barcelona last summer and had been courted by Chelsea and Arsenal, but it was the Craven Cottage side who nipped in to make an “absolute steal”, as ex-Fulham boss Rene Muelensteen put it.
“Chelsea, Tottenham, Liverpool, they saw me, but they didn’t say: ‘We want you,’” Serri explained. “Because Fulham gave me this respect, although other clubs wanted me, I wanted to sign for Fulham.”
Calm on the ball and constantly creating chances for team-mates, he is already looking good and opened his Fulham account with a stunning goal against Burnley when he blasted into the top corner from outside the box.
#9 Leon Goretzka | Schalke to Bayern | Free
Landing Leon Goretzka from Schalke was always going to be a smart signing for Bayern Munich, but getting him on a free proved to be sublime business from the Bundesliga champions.
The 23-year-old midfielder had been a target for Barcelona and said he had “several options” before opting for Niko Kovac’s team.
He made almost 150 appearances for Schalke in the five years since he joined from Bochum, scoring 19 times from midfield and will blossom into a key role alongside Thiago and Thomas Muller.
#8 Thibaut Courtois | Chelsea to Real Madrid | £31m
The Belgian goalkeeper may still have to dislodge last season’s Champions League Goalkeeper of the Year Keylor Navas to seal the No.1 spot at Real Madrid, but few would bet against him doing so in the near future.
The £31m ($40m) signing is set to be Madrid’s long-term option after signing a six-year contract and will settle in easily after enjoying a prosperous spell on loan at Atletico Madrid, while he is also reunited with his family.
The 26-year-old won the Europa League during his time at Atletico and went on to claim two Premier League titles, but will be aiming higher than ever before with the European champions.
#7 Malcom | Bordeaux to Barcelona | £36.5m
The Brazilian winger looked set to join Roma but turned his back on them at the last minute when Barcelona appeared with a €41 million (£36.5m/$48m) offer.
With Lionel Messi occupying the right side, Malcom must compete with Ousmane Dembele for the left wing spot, though he can also play through the centre.
The 21-year-old scored on his first game at Camp Nou as the Catalan side beat Boca Juniors in the Joan Gamper Trophy and will be looking to grow into a first-team role to prove Monchi wrong for declaring that Steven N’Zonzi was the better signing after all.
#6 Axel Witsel | Tianjin Quanjian to Borussia Dortund | £18m
The midfielder shocked Juventus when he rejected them for an offer he couldn’t refuse from Tianjin Quanjian last year, but he couldn’t stay away from Europe for too long,
Although Manchester United were apparently in for the 29-year-old, who also revealed a blocked approach from Bayern Munich, Borussia Dortmund managed to get him after triggering his €20 million (£18m/$23m) release clause.
He already looks a real bargain in the way he is bossing the midfield for Lucien Favre’s side and even scored a fantastic bicycle kick on his Bundesliga debut in a 4-1 win against RB Leipzig.
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#5 Gianluigi Buffon | Juventus to PSG | Free
The chance to sign a World Cup and multiple Serie A title winner on a free transfer does not come up too often, so when Gianluigi Buffon announced his departure from Juventus, it was no surprise to see Manchester City and Paris Saint-Germain become unlikely bargain hunters.
He may be 40 years old, but the Italian picked up a trophy on his first game in the French capital and hopes to keep defying the ageing process.
"If you asked me: 'At age 35, do you feel differently than today?' I would say: 'I think I am better,'” he said this week.
"Then you would say: 'Impossible'. Me too. Sometimes, when I come home, that's what I say to myself: 'It's not possible'. And yet, deep within me, I feel better than five, six or seven years ago. I cannot say why. Maybe because I changed my approach.”
#4 Naby Keita | RB Leipzig to Liverpool | £48m
Excitement about Naby Keita had been building around Anfield long before the midfielder arrived at Liverpool from RB Leipzig and he has looked excellent in the early stages.
“He's unbelievable," team-mate Sadio Mane said. "He's started great and we are here to help him more to get to his best and I am sure he will do something special here.”
The 23-year-old is just getting started, however, and even coach Jurgen Klopp does not know exactly what to expect.
"We all have no clue how good he can be. He's too young to judge him. What can we say?” he said.“I don't want to make it too big, it's just that I don't know. If you asked me what his greatest strength was, I couldn't say it really. It's not because he's not long enough here. But he's a very smart footballer.”
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#3 Jorginho | Napoli to Chelsea | £57m
Italian midfielder Jorginho shook off Manchester City’s interest to follow Maurizio Sarri to Chelsea from Napoli and he has proved imperative in the coach’s playing style taking hold at Stamford Bridge.
“We need Jorginho more than City, so it's right that Jorginho is here," Sarri said at the start of the season. “Jorginho is one of the steps to try to reduce the gap. He's only the first."
He is constantly on the ball and pulling the strings from the middle of the pitch, and his introduction to the team has forced ball-winner N’Golo Kante to move further upfield as part of Sarri’s revolution.
Having already won their first three Premier League games of the campaign, Chelsea are not only competing with City to become the top flight’s pass masters with Jorginho, but the outright champions too.
#2 Alisson | Roma to Liverpool | £65m
The record may not have stood for long, but Liverpool made a big splash this summer when they made Alisson football’s most expensive goalkeeper for £65 million ($83m/€71m).
After seeing him shine for Roma and Brazil, few disputed his value, and Loris Karius’ struggles in the Champions League final made the goalkeeper position a more urgent issue for the Reds.
“The opportunity to sign one of the world’s best goalkeepers [came up] - then it’s not a long thought, to be honest,” Jurgen Klopp said when Alisson joined. “It’s only that you need to have a little talk with the owners! They were quite excited, so we did it. I think it’s something we have to do.”
Alisson has made a great start at Anfield and is seen as the final piece of the puzzle for Liverpool’s title challenge.
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#1 Cristiano Ronaldo: Real Madrid to Juventus £100m
Spending €112 million (£100m/$128m) on a 33-year-old does not sound like a wise investment, but Juventus are confident the landmark signing of Cristiano Ronaldo will pay dividends after luring the global icon from Real Madrid.
As a serial Ballon d’Or and Champions League winner, Ronaldo is expected to help the Bianconeri stay dominant in Serie A and give them enough firepower to get past the final hurdle to European success.
Coming off the back of a season in which he scored 44 goals in as many games in all competitions, the Portugal star is showing no sign of slowing down and will no doubt add a few more trophies to his collection.
Ronaldo was beaten to the UEFA Player of the Year prize by former Madrid team-mate Luka Modric, but for his agent Jorge Mendes, there could only be one real winner: “Football is played on the field and that’s where Cristiano won,” he said. “He scored 15 goals, carried Real Madrid on his back and conquered the Champions League again. It’s ridiculous, shameful. The winner is not in doubt, as Ronaldo is the best in his position.”
Perhaps the upset will only motivate the star to restore his status as the best around even more this season.