If Young Boys' 3-0 loss to Manchester City on Tuesday was not humbling enough, manager Raphael Wicky said he would need to speak with Mohamed Ali after learning his captain had asked City striker Erling Haaland for his coveted shirt -- at half-time.

"I didn't see that, that's news to me and I'm little bit surprised by that right now," Wicky told reporters after the game.

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"On the other hand, I don't think it had anything to do with the game or the performance but I'll probably have a word with him and see what he thought.

"Maybe Erling asked him to swap, I don't know!"

The Young Boys player was spotted approaching Haaland, who had already scored one of his two goals by then, as they headed to the tunnel and the two swapped shirts.

It is not uncommon for players to trade shirts at fulltime, as many City and Young Boys players did at the Etihad Stadium on Tuesday, but half-time exchanges are rare and often incur the wrath of fans who feel it's out of place in the heat of battle.

Former City player Keith Curle told Sky Sports he would "be raging" as a manager.

City manager Pep Guardiola said the swap did not bother him.

"I don't know about it," he said. "We win 3-0. It happened, I don't know the reason why."

Haaland's first goal came from a penalty while Guardiola described his second -- a left-footed rocket from 20 metres -- as "amazing."

"Normally Erling scores goals, six-yard box, 18-yard box he has this talent, not the first time he has done it," the Spanish manager said. "Yeah, that was a fantastic goal."

Guardiola said there was a sense of accomplishment in clinching a knockout berth with two games remaining, but the aim is to finish top in the group to ensure the second game in the last-16 is at home.

"The job isn't done, we have to finish first," Guardiola said. "We have a job to do, the first step to qualify is done. Really impressed, two fantastic goals."