The winger, 26, suffered the knock in Brighton's 1-1 draw with Crystal Palace last week. There are also questions over Ivory Coast winger Simon Adingra's involvement in the Africa Cup of Nations after he hurt his hamstring in the same match.
The Asian Cup, in Qatar, begins on Jan. 12, while the AFCON starts in Ivory Coast the following day.The pair are among up to 10 Brighton players set to miss Thursday's Premier League match at home to Tottenham."Tomorrow we have more or less 10 injured players, maybe eight but (the other) two players can't start the game," Brighton boss Roberto De Zerbi said on Wednesday."
Mitoma is one of them. We lost Kaoru for around six weeks -- four, five, six weeks. Adingra, I think he needs four, five weeks (recovery). Tomorrow, no Mitoma, no Adingra.
"De Zerbi believes Brighton's involvement in the Europa League may be a factor in their long list of injuries but accepts other Premier League managers, including Spurs boss Ange Postecoglou, have faced similar issues."
This season, a lot of injuries were unlucky because (Solly) March, Pervis Estupinan, (Julio) Enciso and Mitoma, they are not muscular injuries," said De Zerbi.
"We are paying maybe for playing every week three times."
"I would like to play with the complete squad but Tottenham played a lot of games without seven, eight players and I never heard Postecoglou cry," added the Italian.
"It's football and we have to accept it."I think we can compete in the same way. Maybe on the bench we have not the same quality with a complete squad but we have maybe more energy with the young players."