The Argentina captain sat out Saturday's La Liga game at the Nou Camp but trained with the squad ahead of Wednesday's Champions League Group C game against Celtic in Glasgow.
Barcelona coach Luis Enrique also welcomes back Uruguay forward Luis Suarez, who missed the Malaga game through suspension, and is expected to take his place in attack alongside Messi and Neymar at Celtic Park.
Captain Andres Iniesta and defender Samuel Umtiti are still unavailable due to injury.
Barca, who are second in La Liga and four points adrift of leaders Real Madrid, can secure qualification to the round of 16 of the Champions League on Wednesday.
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They are two points clear of Manchester City at the top of Group C.
A win at Celtic would guarantee their passage but they will also go through if Borussia Monchengladbach fail to beat Manchester City in the other group game.
(Reporting by Adriana Garcia, editing by Ed Osmond)
