Barcelona spent almost 10 minutes with 10 men vs FC Porto after Lamine Yamal left the pitch

Barcelona spent almost 10 minutes with 10 men during their Champions League clash against FC Porto after youngster Lamine Yamal left the pitch midway through the second-half.

It was another memorable evening for Yamal, who became the youngest player to start a Champions League game at 16 years and 83 days, beating previous record holder Celestine Babayaro.

He once again impressed on the grandest stage, just weeks after making more history by becoming Spain's youngest ever goalscorer in a 7-1 win.

But with 71 minutes on the clock, many eyebrows were raised when he was forced to leave the Estádio do Dragao pitch.

In fact, Barca went on to play a further nine minutes with 10 men before Lamal was substituted by Sergi Roberto in the 80th minute.

Xavi would later explain that a stomach problem was the reason behind his lengthy absence.

"Lamine Yamal felt poorly," the former Barcelona midfielder said in his post-match press conference. "He had been telling me for a while that he wasn't feeling good, that he was feeling sick. That his belly was hurting."

The Spaniard added: "We took advantage of a break [in play], but he was unable to carry on."

Yamal may have left the field of play for a toilet break, but the Catalan giants managed to defend their slender lead and secure a second successive win in this season's Champions League.

Former Manchester City forward Ferran Torres replaced the prolific Robert Lewandowski, who went off in the first-half though injury, and would soon repay his manager's faith with a goal before the break.

After Yamal went off, Gavi was handed a red card in the 93rd minute but they still managed to hold on for a crucial three points in Group H.

“The first half was quite good, but in the second half we suffered. We didn’t play the best game," Xavi said after Wednesday's game.

“It was not our best match, but it was a vital match for us. We won, but we have to play better. We will do it, we will do it.”

He added: “This is the Champions League. And it costs a lot. We won against a historic rival, away from home. We have to emphasize that.”