So, who is shaping up well ahead of the new season? Which players appear to be in top form and peak physical condition ahead of the 2017-18 campaign? And who looks out of shape and out of sorts?!
Below, Goal picks out five men who have impressed in pre-season - and five more who have disappointed...
If there is one man who hasn't been swept up in the furore surrounding the prospect of a player changing clubs for a frankly ludicrous €222 million, it's the subject of the imminent world-record deal, Neymar.
The Brazil international has essentially spent the summer showing why Barcelona will be so sorry to lose him, why Paris Saint-Germain have made an indecent proposal for his services - and why Sergio Ramos will be so glad to see the back of him.
"I hope [he leaves Barca]," the Real Madrid defender said after the International Champions Cup Clasico. "It would mean less problems for us!"
Neymar may not have been at his brilliant best in the 3-2 win over los Blancos but he netted the winner against Manchester United and was simply unstoppable in the Blaugrana's defeat of Juventus, scoring a wonder-goal. He will be missed.
Of course, we already knew that the Selecao star was a class act. What we were unsure of going into the summer was whether Stevan Jovetic still had something to offer at the highest level.
The Montenegrin is probably still heading for the exit door at San Siro but Inter will be very grateful for the fact that Jovetic has produced a most timely reminder of his qualities, given Sevilla had been trying to persuade the Italians to lower their asking price of €13m.
Michy Batshuayi has also done his hopes of securing first-team football this season the power of good over the past few weeks - and not just because he acted as an unofficial agent in Tiemouye Bakayoko's transfer to Stamford Bridge.
The former Marseille striker only arrived at Chelsea last summer and scored the goal that clinched the title but his days in west London nonetheless looked numbered, with the Blues going all out to sign a world-class No.9.
However, credit to the Belgian, he kept his head down, worked hard in pre-season and racked up four goals - including a double against Arsenal - even before Alvaro Morata made his first appearance for the English champions, against Bayern Munich, following his €78.9m arrival from Real Madrid.
Furthermore, while the Spaniard failed to mark his debut with a goal, Batshuayi notched again to suggest that he might actually be capable of putting pressure on Morata this season for the striking role in Conte's three-pronged attack.
However, the competition for places in Liverpool's attacking triumvirate is looking even more intensive right now.
As well as Dominic Solanke looking like one of the bargains of the season, Mohamed Salah has wasted little time in settling into his new surroundings.
The former Roma winger saw little game time at Chelsea under Jose Mourinho during his previous stint in England but, on the evidence of his performances in pre-season - he's already scored four times - the Egyptian looks set to make a big impact on the Premier League at the second time of asking.
Indeed, he not only has the pace and the skills to thrive under Jurgen Klopp at Liverpool, he also has the work-rate.
"He would still be running if we didn't get him off the pitch!" the German joked after watching Salah cover every blade of grass before being replaced in the 2-0 friendly win over Crystal Palace in Hong Kong.
Salah could well prove one of the signings of the season, even at €42m, but that fee only makes Franck Kessie look like even more a steal at €28m for AC Milan.
Ex-Juventus centre-half Leonardo Bonucci undoubtedly represents the biggest coup of the Rossoneri's summer spending spree, a genuine statement of intent from the club's new Chinese owners, but it is Kessie who most impressed for Vincenzo Montella's side in pre-season.
The Ivorian has been a consistently dominant force in the Milan midfield, scoring and particularly impressing in the 4-0 thrashing of Bayern Munich, and talk of him being 'The new Yaya Toure' no longer looks quite so fanciful.
After Gareth Bale pulled out of a Real Madrid training session on Tuesday night, coach Zinedine Zidane insisted: "I'm not worried. He had a bad injury and now he's having a good pre-season. Bale is fine."
Only he's not fine. Bale is rarely fine. He remains an excellent footballer but he also remains utterly unreliable.
At this point of his Real career, the Welsh winger was supposed to be in the process of replacing Cristiano Ronaldo as Madrid's main man.
Instead, after a pre-season blighted by all-too familiar fitness issues and poor performances, he is again being linked with a return to the Premier League.
Manchester United would appear to be the most likely destination.
However, there are already some doubts over their new centre-half Victor Lindelof, who has had a rather underwhelming start to his Old Trafford career.
It could, of course, just be a bit of rust but the way in which the Swedish centre-half completely mistimed his tackle on Theo Hernandez in the ICC clash with Real Madrid was concerning.
When you consider that he was also shown up by LA Galaxy's Giovani dos Santos and taken off at half-time against both Manchester City and Barcelona, it is clear that Lindelof needs to start proving his worth - and soon.
The same goes for Andre Silva. Milan are obviously going to give their €38m signing from Porto time to settle at San Siro but he has looked horribly off the pace in pre-season.
After all, Milan are still hoping to sign another striker before the start of the new season, with one of Nikola Kalinic, Andrea Belotti, Pierre-Emerick Aubameyang or Diego Costa the most likely to arrive.
Still, at least there's a real buzz about San Siro at Milan at the moment. The atmosphere is far more pessimistic in Bavaria, after a dire pre-season for Bayern Munich.
It was hoped that James Rodriguez would lift a side that never really impressed during Carlo Ancelotti's first year at the Allianz Arena - even though FCB won the Bundesliga, again.
However, the loan signing from Real Madrid looked just as inept as all of his team-mates in dreadful defeats to Arsenal, Milan, Inter and Liverpool. And to make matters worse, he picked up a muscular injury versus the latter which will see him ruled out for a number of weeks and miss the start of the campaign.
Indeed, James made zero impact on his side's pre-season campaign - just like Francis Coquelin at Arsenal.
True, Coquelin really sold the club to old friend and new signing Alexandre Lacazette - but the truth is that the club would really love to have sold Coquelin.
However, despite featuring in all but one of the Gunners' friendly fixtures, he did neither enough to convince Arsene Wenger nor any potential buyer that he represents anything other than a sub-standard reserve midfielder.