The Argentina starlet was brimming with confidence going into the clash in Istanbul following his stunning bicycle kick against Everton at the weekend, doing Ronaldo's 'Siu' celebration in the immediate aftermath.
However, the 19-year-old has another for his collection after lashing home a left-footed effort to put the Red Devils 1-0 up.
Galatasaray's supporters had displayed their 'Welcome to Hell' message to Erik ten Hag's side ahead of kick-off and made things very difficult in the early stages by loudly whistling the Premier League side every time they got the ball.
But after firing home 11 minutes in, Garnacho couldn't help but tell the home fans to quiet down, gesturing with his hands for them to settle themselves.
It bears a striking resemblance to the 'calma calma' celebration Man United legend Cristiano Ronaldo did when scoring for Real Madrid against Barcelona at the Camp Nou.
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Garnacho could then he seen cupping his ear as he celebrated the goal in front of the cauldron of noise.
Bruno Fernandes doubled the Red Devils' advantage with a piledriver from 30 yards out on 18 minutes, however, Chelsea loanee Hakim Ziyech's low free-kick pulled one back for Galatasaray.