Sulemana, who was part of Ghana's 2026 World Cup squad, only returned to Atalanta's pre-season last week.
He played 45 minutes in a friendly against Feyenoord which the Italian side lost 2-1. In the second pre-season friendly against Schalke over the weekend, the Ghanaian was subbed on at half-time only to pick up a knee injury 11 minutes later.
The 24-year-old couldn't continue the game and is now set for an extended spell on the touchline after intial tests on Tuesday revealed a second degree tear of the medial collateral ligament (MCL) in his left knee.
Hence, the forward is expected to miss the start of the season and return around December. This means Sulemana could end up missing more than 20 games for Atalanta in the league and cup.
The injury comes at a bad time for both the player and the Bergamaschi as the Italian club were looking to sell the winger this summer.
Sulemana joined Atalanta last summer from Southampton for a fee of €17 milion. He scored three goals and provided two assists in 37 games for the Bergamo-based club.
The Right to Dream graduate suffered two injuries last season for La Dea last season, missing 27 days.
The player is expected to begin rehabilitation as he looks to make a return to action later in the year. Atalanta begin their Serie A journey on August 23 with a home game against Sassuolo.
Ghana will also have to do without Sulemana in the first four games of the 2027 Africa Cup of Nations (AFCON) qualifiers due to the injury.
