Marseille's French midfielder #07 Jonathan Clauss (L) fights for the ball with Nice's Ivorian forward #07 Jeremie Boga (R) during the French L1 football match between OGC Nice and Marseille OM at the Allianz Riviera Stadium in Nice, southeastern France. AFP
"This year he has injured himself in three or four different places in the muscle area, I can't explain," said Haise.
France-born Boga picked up the injury ahead of last Thursday's trip to Brussels for a Europa League game against Union Saint-Gilloise which the French club lost 2-1.
According to his coach, Boga still needs additional tests to determine if surgery is required but club sources have estimated the 27-year-old forward will need at least three months to recover.
Boga is one of 10 Nice players who are absent for the team's Ligue 1 trip to struggling Montpellier.
Nice are sixth in the league table.
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