Pierre-Emerick Aubameyang and Christian Pulisic could miss Borussia Dortmund's match at Hannover 96 this weekend.
In their midweek DFB-Pokal match at Magdeburg, Dortmund picked up their first win in three matches, but had to do so without top scorer Aubameyang, United States international Pulisic and Mario Gotze. BVB cruised to a 5-0 win, but only opened the scoring after 42 minutes.
"The confidence returns when you take a 2-0, a 3-0 lead," manager Peter Bosz said, but added that Dortmund might once again be without Aubameyang and Pulisic as they continue to recover from minor knocks.
"Mario could have played. It's no problem. But with Auba and Chris we'll have to wait see after the final training session today. I'll decide after that whether they'll make the squad."
In case Aubameyang misses the trip to Hannover, 18-year-old Alexander Isak could make his first Bundesliga start for Dortmund after scoring against Magdeburg.
"Isak's an option. Several players could replace Auba. But let's first see what's up with Auba," Bosz said. "Auba's been a key player for Dortmund for several years. Isak is very young, he only turned 18, only came here in January. He's a very talented player, and every minute he plays is important for him."
Despite the midweek high, Borussia Dortmund blew a five-point lead at the top of the Bundesliga table in two league games and, going into this weekend, only remain in top spot ahead of Bayern Munich (who they face next week) on goal difference.
Sixth-placed Hannover have already picked up 15 points from their first nine matches and, although they have only managed to score four goals in as many home games, Bosz insists it will be a tough game.
"They are not your average promoted team," he said. "They are a dangerous side, even though they don't have a lot of shots on goal. It's incredibly hard to beat them. This will be a challenge."