Borussia Dortmund is waiting on the fitness of defensive chief Mats Hummels for Tuesday's Bundesliga top-of-the-table showdown at home to leaders Bayern Munich.
The 2014 World Cup winner aggravated his Achilles tendon in Saturday's 2-0 win at Wolfsburg which kept second-placed Dortmund four points behind leaders Bayern, who are chasing an eighth straight league title.
Hummels came off at half-time on Saturday, but Dortmund still hope he can lead the hosts' defence against his former club Bayern.
"Mats has a problem with his Achilles tendon and we hope he can play on Tuesday," said Dortmund sports director Michael Zorc.
"He has had the problem for a while."
Hummels was treated at Dortmund's training ground on Sunday and if he is not fit, Emre Can, who replaced Hummels in Wolfsburg, will deputise against Bayern.
In the Munich squad, there are question marks over midfielder Thiago Alcantara and defender Jerome Boateng.
Alcantara sat out Saturday's 5-2 thrashing of Eintracht Frankfurt in Munich with a groin strain.
Boateng came off late in the second-half with a muscular knock.
Bayern hammered Dortmund 4-0 at the Allianz Arena in Munich when the teams last met in November.
The Bundesliga became the first top European league to return during the COVID-19 pandemic last weekend with all matches played behind closed doors.