Lamine Yamal was forced off with an injury immediately after scoring a penalty in Barcelona's LaLiga win over Celta Vigo on Wednesday at Spotify Camp Nou.
Yamal, 18, won and converted a spot kick to give Barça the lead, but rather than celebrate the goal, he immediately dropped to the ground and called for the medical staff.
Replays showed the Spain international grabbing his hamstring after scoring the penalty that proved enough to give Barcelona victory.
After receiving treatment on the pitch for a few minutes, he was able to walk off, but he was not able to play on. Roony Bardghji replaced him just before halftime.
After the goal, the game was also halted for almost 20 minutes because of a medical emergency in the stands.
The match eventually restarted once the affected supporter had been evacuated from the stadium, according to an announcement, with the match clock ticking beyond 65 minutes before the halftime whistle eventually sounded.
Barça can ill afford to be without Yamal for any stretch of time as they attempt to get over the line in LaLiga.
Wednesday's victory took Barcelona nine points clear of second-place Real Madrid with six games remaining.
Barça and Madrid still have to play each other, with the two rivals meeting in the second LaLiga Clásico of the season at Camp Nou on May 10.
Yamal has struggled with a pubalgia issue at times this season but has not missed many games through that groin pain or other injury, making 45 appearances in all competitions.
Wednesday's goal took his tally for the campaign to 24, and he has also provided 17 assists.
His injury will also be a concern for Spain ahead of the start of their World Cup campaign on June 15.