Finding the 'new Dani Alves' is no easy task. Even locating the 'old Dani Alves' is difficult, as Pep Guardiola's Manchester City discovered to their cost over the weekend.
Still, Barcelona are hoping that they have, at least, succeeded in the former challenge, with the club confirming the signing of Nelson Semedo from Benfica on Friday.
A Barcelona delegation led by sporting director Roberto Fernandez flew to Lisbon on Thursday and agreed a deal which will see the Catalans pay an official €30m - and a further €5m in bonuses.
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The Blaugrana had, of course, made Hector Bellerin their primary target to fill the void left by Dani Alves when he departed for Juventus on a free transfer last summer and prophetically proclaimed: "You will miss me once I'm gone."
Indeed, for all Sergi Roberto's enthusiasm, the right-back berth was Barca's problem position last season, with injury having interrupted Aleix Vidal's hopes of a regular run of games.
Bringing La Masia graduate Bellerin back to Catalunya obviously made sense on a number of levels for the Blaugrana board but, in a summer in which Arsenal look set to lose Alexis Sanchez to Manchester City, they were never going to allow the Spain international depart too.
As a result, Barcelona have hastily turned their attention back to Semedo.
Benfica had already rebuffed the Blaugrana's opening bid of €30m for the 23-year-old, insisting that they would accept nothing less than €50m, but a compromise was eventually reached late on Thursday evening.
It was not in the least bit surprising, given that Javier Bordas, the member of the Barca board authorised to make offers, had travelled with Fernandez to the Portuguese capital. With their pursuit of Paris Saint-Germain midfielder Marco Verratti set to drag on all summer, the Catalan contingent wanted to wrap up a deal for Semedo as quickly as possible.
The final fee may be excessive but this is, after all, a player who also attracted the attention of Manchester United boss Jose Mourinho after a season which ended with the defender being named the Primeira Liga's Breakthrough Player of 2016-17.
The Lisbon native is certainly something of a late bloomer, having only forced his way into the Benfica senior side after spending the majority of his time at the Estadio da Luz with the club's B team.
Semedo was always considered an immensely promising prospect but there were doubts over his consistency, concentration and positional sense.
However, he kept his head down, continued to work hard on his game and bided his time.
It arrived in the summer of 2015, impressing so much after breaking into the Benfica first team that he was called into the Portugal squad for the Euro 2016 qualifiers against Denmark and Serbia.
Then, disaster struck, with Semedo suffering a knee injury in training while on international duty that he struggled to recover from.
He went from rubbing shoulders with Cristiano Ronaldo to back to the Benfica B team by the end of the 2015-16 season.
Last year, though, Semedo excelled. He was one of Benfica's most reliable performers during a campaign in which they won both the Primeira Liga and the Taca de Portugal.
Indeed, the once error-prone youngster didn't make one mistake that even led to a shot, let alone a goal.
What really caught the eye, though, was his attacking play. Semedo is very much a modern full-back, one who always looks to move forward.
No other defender attempted (105) or completed (49) more dribbles in the 2016-17 Primeira Liga, while only Alex Telles bettered his tally of six assists.
He is certainly not a huge goal threat - though he did score twice, including one stunning strike in the Champions League draw at Besiktas - but, with his pace, skill and quick feet, he moves like and creates as many openings as an orthodox winger.
Therefore, it did not come as surprise to see Fernando Santos award him the No.11 jersey for Portugal’s Confederations Cup campaign this summer.
The tournament ended on a bittersweet note for Semedo, who was sent off in the Seleccao’s win over Mexico in the third-place play-off, and his dismissal merely underlined that he still has much to learn.
However, if there is one thing that Semedo has already shown, he has the requisite mental strength to recover from a setback.
It might also help him to cope with the Dani Alves comparisons which are bound to come his way after completing his move to Barcelona.
Semedo is a dogged, determined character and an excellent attacking full-back.
In truth, finding the ‘new Dani Alves’ is probably impossible. But Barca might just have discovered the next best thing.