Borussia Dortmund may have to make do without the services of Ilkay Gundogan and Marco Reus when they take on Ingolstadt in the Bundesliga this weekend.

The duo are being plagued by illness ahead of Saturday's encounter and could be forced to sit out, while Marcel Schmelzer is also unlikely to feature.

Dortmund will close the gap to leaders Bayern Munich to five points with a victory, with Pep Guardiola's side not in action until their home meeting with Hoffenheim on Sunday.

"Ilkay Gundogan and Marco Reus have caught a virus and we will have to wait on how that pans out," Dortmund head coach Thomas Tuchel said at a media conference.

"Marcel Schmelzer is not feeling well either, so we might be without him as well. Erik Durm on the other hand is raring to go again and is a candidate to start."

Reus paid former Bayern doctor Hans-Wilhelm Muller-Wohlfahrt a visit in midweek to have an adductor injury looked at, but Tuchel was quick to stress there is no fresh concern.

"Reus' visit to Muller-Wohlfahrt was a routine check-up," he added.

"We simply made the most of the opportunity now that we did not have an extra game in midweek. There is no problem."

Dortmund lost Adnan Januzaj and Jonas Hofmann this month to Manchester United and Borussia Monchengladbach respectively and Tuchel still hopes they can bring in at least one new attacker before the end of the January window, although he realises it will not be easy.

"We are very calm about the transfer market. The winter is complicated and a small window," he stressed.

"We allowed two players to leave, two attacking players, and I said it would be important for me to replace them with quality.

"That was my wish as a coach, but I knew how hard it is in the winter. The players you buy have to be released elsewhere."