Zurich - Lionel Messi's appeal against a four-match ban in World Cup qualifying for insulting a referee's assistant was being heard by FIFA on Thursday.
Messi, who was to testify by video, is not expected to get an immediate verdict.
The FIFA appeals panel typically gives a detailed verdict within weeks in non-urgent cases. Argentina's next World Cup qualifier is at Uruguay on August 31.
Messi already served one match of the ban that was imposed when the FIFA disciplinary committee gave its ruling hours before Argentina's 2-0 loss in Bolivia in March.
FIFA was able to ban Messi after match officials did not report the Argentina captain for verbally abusing a linesman late in a 1-0 win over Chile on March 23.
FIFA disciplinary rules require a sanction "at least four matches for unsporting conduct toward a match official."
Previous FIFA verdicts have resulted in a player getting at least one match of the ban suspended on probation.
In a similar case from a South American qualifying game last September, FIFA also banned Chile midfielder Gary Medel for four matches after he was shown a red card for verbally abusing a referee. However, FIFA deferred one game of the sanction for a two-year probationary period.
A 2014 World Cup case ruling also offers hope for Messi and his lawyers.
Fernando Santos, then coaching Greece, was initially banned for eight matches for verbally using officials during a last 16 loss against Costa Rica in Brazil. When Santos, by then coaching Portugal, appealed at the Court of Arbitration for Sport, the ban was reduced to four games. Two of those games were deferred for six months of probation.
Messi is currently banned also for home games against Venezuela on September 5 and Peru on October 5.
Argentina is fifth in the 10-team South American group with four games left. The 2014 World Cup runners-up are currently in line to advance to a November playoff against a team from Oceania, likely to be New Zealand.