Brighton boss Fabian Hurzeler has confirmed Mats Wieffer will be sidelined until next month with a knee injury.
The right-back was forced off during Brighton's 4-3 defeat by Chelsea after being struck in the face by the ball, causing him to lose his balance and injure his knee.
Hurzeler explained the unusual injury by comparing it to a boxer being knocked off balance.
"I can explain this quite easily because I also like to watch boxing," Hurzeler said.
"Sometimes in boxing, when someone gets like a hit, then you see how weak his legs go and then the legs get in very strange positions and then it might happen that your knee gets injured or your ankle gets twisted.
"It was a similar situation with Mats where he got a hit with the ball in his face and then he lost a little bit the control of his body.
"Then his legs got in a strange position then this injury happens. Luckily, it isn't a bad one. So we hope that he will be back on the pitch quite quickly.
Georginio Rutter and Yasin Ayari could be involved against Leeds on Saturday, however.
"Georginio and Yasin Ayari might be options for tomorrow," Hurzeler said.
New signing Femi Azeez is also carrying a slight injury and will be assessed over the weekend, while Kaoru Mitoma could return next month after the international break.
" Femi Azeez is obviously carrying a slight injury at the moment. I think Chema (Andres) can definitely be an option for tomorrow.
"With Femi, we have to wait this weekend and hopefully he will be available for the next game.
"Kaoru Mitoma will be back after international break, we have to be patient. Hopefully our wingers can come back quickly."
