Thomas Muller suffered bruising to his thigh in Bayern Munich's 6-0 DFB-Pokal quarter-final win over Paderborn, head coach Jupp Heynckes has confirmed.
The Germany international was replaced by Corentin Tolisso after 32 minutes of Tuesday's match, with Bayern leading 2-0.
Heynckes says the forward was taken off as a precaution and expects updates on the problem over the coming days.
"Muller has a bruised thigh so we'll have to see how the injury develops over the next few days," he said. "He could have carried on, but was restricted and unable to give his maximum."
Muller's injury did not prove a hindrance to Bayern, with Joshua Kimmich, Tolisso and an Arjen Robben double adding to Kingsley Coman and Robert Lewandowski's earlier goals to secure their semi-final spot.
"Of course, everyone is delighted that we have qualified for the next round," said Heynckes. "We dealt with the difficult surface very well, scored wonderful goals and deserved the win."
Kimmich was impressed with the way the 3.Liga leaders performed at Benteler-Arena, despite the one-sided nature of the scoreline.
"They played really bravely," he told Sky. "Huge compliments to Paderborn. They tried to play football on this surface."
Paderborn coach Steffen Baumgart added: "It's impressive how they take advantage of things. We tried, but the opposition was too big for us."
