Bayer Leverkusen coach Roger Schmidt has confirmed Karim Bellarabi requires surgery on the groin injury he suffered against Hamburg at the weekend.
Bellarabi, 26, picked up the injury seconds into the Bundesliga game and is now facing a spell on the sidelines.
"Karim Bellarabi will be out for a couple of months and will undergo an operation in Basel tomorrow," Schmidt said at a news conference ahead of Leverkusen's Champions League game against CSKA Moscow.
"Vladlen Yurchenko has a fractured leg and Kevin Volland isn't quite up to full speed yet. He's fit enough to make the squad, but we'll have to wait and see on that one."
Meanwhile, Joel Pohjanpalo may not have done enough to earn a starting spot despite scoring a hat trick as a substitute during the game against Hamburg.
It was the 22-year-old's second appearance for the club and Schmidt could opt to continue easing him in slowly.
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"Joel has been superb lately and showed on Saturday how strong he is in the box," Schmidt said. "Whether he'll start tomorrow remains to be seen, but he's definitely in contention.
"If you get the better of the likes of Zenit in the league, you must be a good team. CSKA have shown recently how difficult they are to beat. I think the Hamburg win was superb preparation for tomorrow's game, and I hope we can pick up where we left off on Saturday."
Leverkusen captain Lars Bender is excited at the prospect of Champions League football coming to the BayArena for a fourth successive campaign.
"The Champions League is always something special, even if we've been here before," he said. "For a long time it didn't look like we'd qualify automatically for the group stage, so we're very happy to be here. We're hoping tomorrow will be a special evening.
"We've got some difficult games coming up. It's just as important to get off to a good start in the Champions League as it is in the Bundesliga.
"We did well to come from behind to win on Saturday and we want to carry that momentum into this game."