Barcelona manager Xavi has confirmed that Lamine Yamal was struck down by illness during Wednesday's victory over Porto.
On what was his first Champions League start, 16-year-old Yamal disappeared down the tunnel 71 minutes into the 1-0 win and was not replaced until the 80th minute, leaving the team with ten men for a significant passage of the game.
After the game, Xavi confirmed to Movistar+ that the teenager was unwell and was ultimately not able to return to the pitch.
"He felt sick, he was unwell," Xavi said. "He had a very bad pain in his stomach, he had been telling me for a while.
"I took advantage of a break to tell him to be quick and go to the toilet, but in the end they told me that he wouldn't be able to get back on the pitch."
Earlier in the game, Barcelona lost striker Robert Lewandowski to injury, with the Poland international limping off after 34 minutes.
"He took a very bad blow to his ankle that did not allow him to continue," the Barca boss explained. "Let's see if he is recovered for Sunday [against Girona]."
Xavi, who completed his 100th game as Barcelona manager, will now be sweating over the condition of both players as his side prepare for a tough clash against La Liga highflyers Girona.
Girona sit third in the standings, just one point behind Barcelona and a further point adrift of league leaders Real Madrid.
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This article was originally published on 90min as Xavi explains bizarre Lamine Yamal exit during Porto victory.