Liverpool summer signing Emre Can was forced to withdraw from the Reds' preseason friendly against Preston North End after just 20 minutes of Saturday's match.
The 20-year-old, who joined from Bayer Leverkusen, was replaced by Jordon Ibe before making a prompt exit down to the tunnel to receive further treatment.
No obvious challenge caused the injury, which is believed to be a calf strain, and Can was clearly in some discomfort before heading off the pitch.
The injury could be a major blow for Brendan Rodgers, who paid Leverkusen 12 million euro to acquire the young star, as it remains to be seen whether the problem will cause Can to miss the start of the Premier League season.
Liverpool kicks off its campaign against Southampton at Anfield on August 17, a match in which the club's other summer signings could make their bow.
Along with Can, Rodgers has brought in Rickie Lambert, Adam Lallana and Lazar Markovic following the departure of Luis Suarez and is set to announce the signing of Loic Remy, who has agreed to join the club from QPR.