Callum McGregor knows Borussia Dortmund were a step too far for Celtic at Champions League level, with the Scottish champions suffering a "sobering" night in Germany.

The experienced midfielder confessed the Hoops just couldn't execute their game plan as they lost 7-1 at Signal Iduna Park. 

"It's a sore one," the Celtic captain told TNT Sports. "Every mistake we made, we were punished pretty much.

"That doesn't happen often in a game of football but before we know it, we are 5-1 down, and like I said every little mistake was punished. Like you said a sobering night, but you make mistakes like that, you get punished.

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"Credit to Dortmund, they showed really good quality, really good idea of the game, but we have to stick together. We have had a good start to the season, we've come here, we've been sobered a little bit. But we have to take that and keep the group together then bounce back in the next game."

Celtic conceded 94 seconds after Daizen Maeda had levelled and McGregor understands that shouldn't have been allowed happen. 

"We get back into the game, and you think 'here we go now we play the game from one each' then the quick goal kills us and I think it rattled us in a way. 

"We then started going alone when trying to win the ball back and coming out our shape a bit. When you give good player's the ball, they will kill you, and that's what they did." 

More to follow...