The 24-year-old had started the game well, in line with his excellent form of late, and as a result this comes as a big blow to both the player and his club.
“That was really unlucky, bad news he has a high-grade adductor injury, and the tendon is ruptured,” he said.
“Which keeps him out for at least two months, so bad news for us and bad news for Guinea as well, because the Africa Cup of Nations is coming up.
“[He] was in a really good moment, really, really good moment, but it happened, that’s how football and life sometimes is.
“Not too nice, but very serious.”
Asked about Keita’s mentality as he faces another layoff, which is likely to keep him out of the Africa Cup of Nations, the manager described it as “a moment when you have to help the players.”
“For sure he’s not in the best moment, but it’s OK,” he continued.
“Two things, a very interesting part of the season he’s not part of, and Guinea is not a regular starter in the Africa Cup of Nations [finals], that was for sure a big target for him as well.
“Of course he’s not in a good moment, but that’s a moment when you have to help the players.”