So how did Alexander Buttner get on up against Arjen Robben?
It seemed like the biggest mismatch at Old Trafford since Antonio Valencia took on Andre Santos.
Arjen Robben up against Alexander Buttner appeared like a one-sided bout which if a boxing match would not have been tipped to last beyond the opening rounds.
And if you had stated before the game that Buttner would complete a woeful 33 per cent of his passes, and be substituted on 74 minutes despite the bench not consisting of a left-back, then you would only assume all the worst fears to be true.
Except the pass statistic did not tell the whole story, nor did the substitution alone, taken off with a muscle injury.
Arjen Robben was not allowed the freedom he would have desired, with Buttner making two successful tackles and one interception.
Yet even those figures do not do Buttner justice. He pressed Robben all game, and was tactically astute, keeping tight to the central defenders.
His energy even made fan forget about the suspended Patrice Evra, and after this display, the Frenchman's return for the second leg is no longer assured, leaving David Moyes with a tough decision.
Here is a look at how fans reacted to the 25-year-old's performance:
Buttner did the job and kept Robben at bay tonight. We've got one foot in the door now. Lol at everyone who wrote us off before KO! #MUFC— United We Stand (@uni7edwestand) April 1, 2014
Buttner played better than Evra has all season tonight. #mufc— Peter Hall (@PeteHall86) April 1, 2014
I thought Buttner was good tonight. I doubt Evra would've done better #MUFC— Mrs Balcázar (@GirlMufc) April 1, 2014