Kaoru Mitoma will miss Brighton's trip to Nottingham Forest in the Premier League this Saturday.
Roberto De Zerbi has confirmed the club's decision on the Japanese winger despite him being pictured in training ahead of the game.
Mitoma withdrew from Japan's recent internationals against Myanmar and Syria due to injury but there were hopes he would be back in time for Brighton's return to action.
However, De Zerbi said on Friday that he will be unavailable along with James Milner and a number of other Brighton players.
"Mitoma and Milner can’t play, they are not available," he told reporters.
"We will have to see with Igor [Julio].
"We have too many injuries – I have lost count! [Lewis] Dunk is available, [Pervis] Estupinan isn’t – I think for a long time."
Mitoma, 26, is yet to miss a game for the Seagulls this season and has a haul of three goals and four assists to his name in all competitions. He joins Julio Enciso, Solly March and Danny Welbeck on the sidelines this weekend.
Yet, as well as the fit-again Dunk, Brighton will have Tariq Lamptey in their squad along with Jakub Moder, who has not yet played this season due to a serious knee injury.
In eighth place after failing to win any of their last six league games, De Zerbi is adamant things will improve for his team.
"It’s tough at the moment but I don’t like to cry," he said. "I think we have enough to get points tomorrow and qualify in the Europa League. We have to keep pushing."
