Lionel Messi is one of the last vestiges of the true one-club man, having spent his nearly two-decade-long career at Barcelona. After his contract with the Blaugrana ran out this summer, he was widely expected to re-sign with the only club he has ever played for.However, things didn't pan out that way. Due to La Liga's fair play regulations, Barcelona, who are already in massive debt, needed to jettison several players to be able to accommodate Messi's contract extension. That didn't happen, though, despite Messi reportedly agreeing to take a 50% pay cut. It left Barcelona with no option but to bid a reluctant adieu to their prized asset.🗣 @JoanLaportaFCB: "Leo wanted to stay and the Club wanted him to stay"The reasons for Leo Messi's departure 👇https://t.co/U2JDD9a6AE— FC Barcelona (@FCBarcelona) August 6, 2021During a 17-season stint with Barcelona, Messi made over 900 goal contributions and scored more than double that of the next most prolific scorer for the club. He also won individual and team honors galore.With the six-time Ballon d'Or winner all set to play for another club now, it remains to be seen which player dons the Argentine's #10 jersey at Barcelona. Under La Liga's rules, the Blaugrana may not receive permission to decide to retire the number altogether. On that note, here's a look at five Barcelona players, in no particular order, who could inherit the club legend's #10 jersey next season:#5 Ansu FatiAnsu Fati in action for BarcelonaAnsu Fati is one of the most exciting graduates to have emerged from Barcelona's famed La Masia academy in recent years. After making a record-breaking debut for Barcelona in 2019-20, the 18-year-old missed large swathes of last season because of injury.Fati, the youngest ever player to score in the Champions League, has already scored 13 times and provided five assists. He made a promising start to life under Ronald Koeman last campaign before enduring a season-ending injury that required surgery.2 - Barcelona's Ansu Fati is the first player ever to score more than one Champions League goal before turning 18. Talent. pic.twitter.com/pB2KaTU264— OptaJoe (@OptaJoe) October 20, 2020Considering his stellar exploits, which exceeds that of Messi at the same age, Fati could be the new #10 at Barcelona. The Argentine said of the player when Fati first arrived on the scene two years ago:"I really like him, and I try to help and support him. He's an amazing player and he's got what it takes to succeed. But if I look at it through my eyes, I'd like them to bring him on gradually, like they did with me when I started, taking things nice and easy and without putting pressure on him."You have to remember that he's only 16. I hope he keeps on enjoying it and that all the fuss around him doesn't have a negative impact on him because he has the quality to become one of the best."#4 Sergio AgueroSergio Aguero at his Barcelona unveilingSergio Aguero appears to be one of the more likely successors of Lionel Messi's #10 jersey at Barcelona.After leaving the Premier League as its most prolific non-English goalscorer, the former Manchester City striker hoped to play alongside his good friend Lionel Messi at Barcelona. Aguero joined the club on a free transfer earlier this summer.OFFICIAL: Sergio Aguero joins Barcelona 🚨 pic.twitter.com/ptenrM1dMj— B/R Football (@brfootball) May 31, 2021However, with Messi leaving the club, Aguero's wish to play with Messi in club football will remain unfulfilled for a while. But considering his stellar exploits with Manchester City while wearing the #10 jersey, Aguero could don the same number at Barcelona too.