"He will be sidelined for an estimated four to six weeks. He will undergo further examination (on Wednesday)," Marseille said on their website (www.om.net).
Valbuena will miss at least three league games with fourth-placed Marseille and next week's final Champions League Group F match at home to Borussia Dortmund.
Last year's Champions League runners-up Dortmund will secure a knockout stage spot if they win or match Napoli's result at home to group leaders Arsenal. Marseille, who have so far lost all their five matches played, are already eliminated.