Borussia Dortmund striker Paco Alcácer will be facing a race against time to be at full fitness ahead of the Champions League in midweek after the Barcelona loanee suffered a thigh injury on his Bundesliga debut.
The 25-year-old came off the bench during the second half in Dortmund's flattering 3-1 win over Eintracht Frankfurt on Friday, and Alcácer even got on the scoresheet after his powerful left-footed strike deflected past Kevin Trapp to round off the scoring at the Westfalenstadion.
However, the excitement Alcácer's highly anticipated debut has since disappeared after it was confirmed by manager Lucien Favre that the Spain international had suffered a mysterious injury at the end of the match.
"We definitely do not know what he has, but he felt something in his thigh," Favre said, quoted by Bild. "We hope it's not a strain."
There has since been some speculation that Alcácer actually suffered an ankle injury during his competitive debut for Borussia Dortmund, as opposed to a thigh strain which Favre initially alluded to.
Regardless, Alcácer will likley be forced to miss the club's Champions League opener against Club Brugge on Tuesday, with Maximilian Philipp expected to retain his place in the first team when Dortmund travel to the Jan Breydel Stadium in Belgium.
Borussia Dortmund's win on Friday has seen them move top of the Bundesliga table, but Bayern Munich can reclaim top spot when they take on Bayer Leverkusen - who are without a point this season - on Saturday.
One of VfL Wolfsburg or Hertha BSC will be able to overtake Borussia Dortmund when they face each other this weekend, while four other Bundesliga sides can also leapfrog Die Schwarzgelben on goal difference.