A statement from Barca on Friday said Brazilian Arthur, who played 90 minutes in the 1-1 draw with Real Madrid in a Copa del Rey semi-final first leg on Wednesday, would be out for between three and four weeks.
Arthur, who has quickly adapted to the Barca team since joining from Brazilian side Gremio last year, will miss the Cup semi-final second leg with Real on Feb. 27 and the Champions League last-16 first leg at Olympique Lyonnais on Feb. 19.
He will also be sidelined for league games against Athletic Bilbao, Real Valladolid and Sevilla and faces a battle to be fit for the league 'Clasico' away to Real Madrid on March 2.
Barca captain Messi, the league's top scorer with 21 goals, is a serious doubt for Sunday's testing trip to Athletic Bilbao after missing Friday's training session with the thigh strain which made him unable to start the Cup game against Real.
Left back Jordi Alba has already been ruled out of the game at Bilbao due to suspension and Ousmane Dembele has not yet recovered from an ankle injury.
(Reporting by Richard Martin, editing by Ed Osmond)
