Callum McGregor left 'embarrassed' after Celtic's heaviest Champions League defeat since 2017

Callum McGregor admits he was left "embarrassed" after Celtic suffered their heaviest Champions League defeat in six years against Atletico Madrid.

The Hoops were thrashed 6-0 by Diego Simeone's side at the Civitas Metropolitano Stadium to continue the Scottish champions dismal record in against Spanish opposition in the country.

Daizen Maeda's controversial early red card with the visitors trailing 1-0 at the time through Antoine Griezmann's sixth-minute opener left Brendan Rodgers' men with a mountain to climb and effectively killed the game.

It presented the La Liga outfit with a perfect opportunity to rack up the goals in front of their own supporters as they dished out Celtic's worst defeat since losing 7-1 to PSG in November 2017.

Skipper McGregor offered no excuses for the defeat as he lamented yet another red card on their travels in Europe, having been reduced to nine men on Matchday one away to Feyenoord.

Speaking on TNT Sports, he said: "It was a really tough night for sure. Embarrassing to lose six goals. We have to learn quickly. That has to be a one-off.

"We've now come to two away games and had men sent off in both games. At this level, it's difficult enough 11 vs 11 and that's not to point fingers at anyone because I think there hasn't been any malice in any of three challenges.

"The threshold is now so low for red cards, we have to adjust the way we are defending. But we have to learn from that, that's two games in a row now away from home we've gone down to ten and nine men."

Doubles for Griezmann and Alvaro Morata plus additional strikes from Samuel Lino and Saúl Ñíguez left Celtic licking their wounds.