Lionel Messi trained at the Ciutat Esportiva on Wednesday despite Barcelona's first team being given the day off.
His desire to return has been the key to a quick recovery -- he was initially ruled out for three weeks when he broke a bone in his arm against Sevilla on Oct. 20.
Messi travelled to Milan but watched Barça draw with Inter from the stands on Tuesday before returning to Catalonia after the game and training at 11am on Wednesday.
Still without the green light from the club's medical team, Barça's privileged position in the Champions League (they were three points ahead of Inter before the game and qualified for the last 16 with the draw) mean they didn't have to take any risks.
However, the fact that Messi trained on Wednesday suggests he could play against Real Betis on Sunday -- Barça's final game before the international break.
Barça go into the game at the top of La Liga, while Real Betis are 14th in the table after drawing 3-3 with Celta Vigo in a thrilling game over the weekend.