"He was waiting for quite a long time, he was deserving (of his chance)..."
The 22-year-old put in the type of performance United fans had expected to see when he joined the club from Southampton for £30m in 2014.
While the Red Devils had Romelu Lukaku and Marcus Rashford to thank for the goals that ensured they topped the group, it was the left-back's surprise inclusion in the starting XI that set tongues wagging at Old Trafford. It is not easy to give an opportunity to a player that does not play for many months in matches where the team really needs results.
The reasons behind his exile have been well-documented, not least by Jose Mourinho himself, who rarely misses an opportunity to criticise the England global in public.
He said: 'It's hard to say as we don't see what goes on behind the scenes.
"I can't think of a left-back like that who can change the pace of the game as quick as he does". I don't think he lives his life as clean as he possibly should do. "If I get the chance to play".
"I'm always honest. I thought really that he wouldn't play, that was what I had been told".
While this Sunday's Manchester derby may come too soon for Shaw, it's highly likely Mourinho will fancy him for upcoming league games against Bournemouth and West Bromwich Albion as well as the Red Devils' League Cup quarter-final against Bristol City.
Paul Pogba, who had starred in United's 3-1 win over Arsenal on the weekend before getting sent off for a rash challenge, was running the show once again and his through-balls to the galloping Shaw were creating havoc on the wings.