RB Leipzig will be without Tyler Adams for the first leg of their Champions League last-16 tie with Tottenham.
Head coach Julian Nagelsmann announced at a news conference on Thursday the United States international sustained a calf injury in training and will be out for at least a week.
Leipzig face Werder Bremen in the Bundesliga on Saturday before taking on Jose Mourinho's Tottenham in north London four days later.
Adams, who turns 21 on Friday, has made five appearances in all competitions this season, having only returned from seven months out with a groin issue in December.
He started the 0-0 draw with Bundesliga leaders Bayern Munich on Saturday that left Leipzig winless in four games in all competitions.
However, Nagelsmann is confident his team are primed to reproduce their best form as they hit a crucial part of the season.
"Our football improved against Bayern. It's a step in the right direction. The game has given the players confidence; training has been full of determination and power this week," said Nagelsmann.
"The team lacked stability before Bayern. There have been a lot of new elements in training in recent weeks that challenged them.
"I'm confident we can shake off this mini struggle, though, and believe that we already have."