Argentina are unable to retire the No.10 shirt in honour of Lionel Messi due to FIFA rules.However, they can still honour his legacy by leaving the shirt vacant for non-tournament fixtures.Messi is set to bring down the curtain on his illustrious international careerShutterstock EditorialMessi will make his final appearance for his country against Benin in a friendly on Tuesday.It follows his decision to retire from international football last month.The 39-year-old is Argentina’s all-time leading scorer and appearance maker with 125 goals in 207 caps.He has also won the World Cup and two Copa Americas since making his senior national team debut aged 18 in 2005.Messi has worn the iconic No.10 shirt for Argentina since 2009, having previously worn both 18 and 19 at his first two major tournaments.Following Juan Roman Riquelme’s retirement, though, he inherited the jersey, which has remained as Messi’s since.Can Argentina retire Messi’s No.10 shirt?However, the Argentine Football Association (AFA) will not be able to officially retire the No.10 shirt despite president Claudio Tapia expressing his desire to do so.FIFA’s international tournament rules require teams to assign numbers in order to each member of their squads.In practice, this saw the 26-man squads at the World Cup handed numbers from one to 26.As a result, Argentina will have to assign the No.10 shirt at World Cup finals and the Copa America in future even in Messi’s absence.The AFA’s plans to honour Messi’s legacy are currently being blocked by FIFA rulesGettyThere remain ways to honour the eight-time Ballon d’Or winner away from major tournaments, though.The shirt can be left unused for international friendlies and World Cup qualifiers.Argentina did not issue the No.10 for Wednesday’s friendly win over Bolivia, with Messi not part of the squad.This will also be the case against Burkina Faso on Saturday ahead of Messi’s farewell game three days later.As well as Messi and Riquelme, the No.10 shirt was also previously worn by legendary figures Mario Kempes and Diego Maradona.The AFA similarly tried to retire it in Maradona’s honour following the end of his international career.Argentina previously tried to retire the No.10 shirt four years before Messi’s debutGettyPrior to the 2002 World Cup, Argentina submitted a request to FIFA for permission to leave the No.10 shirt vacant at the tournament.However, their request was denied, with midfielder Ariel Ortega ultimately issued with the jersey.Who could be Argentina’s next No.10?It has not yet been decided who will succeed Messi as Argentina’s No.10, says manager Lionel Scaloni.Speaking to reporters earlier this week, he admitted: “We aren’t obligated to assign it for these matches, so we won’t give it to anyone until Leo’s farewell game.“The idea is for someone to eventually take it on, given how special it is to wear. We just haven’t decided who yet.”Real Madrid youngster Franco Mastantuono, who is currently on loan at Fiorentina, has previously worn the No.10 jersey in Messi’s absence.Scaloni is yet to decide who will inherit the No.10 shirt, with Nico Paz in the runningGettyThe 19-year-old donned the No.30 against Bolivia this week, though, as he featured off the bench.Meanwhile, Como’s Nico Paz has also been tipped as a successor to Messi’s throne and wore his old No.18 as he scored in the 4-0 win in Cordoba on Tuesday.