Darmian has only started once since the turn of the year, while Rojo – seemingly always injured – has played just four times this season, his only Premier League start coming back in November against Arsenal.
Darmian is the obvious choice here. The Italian has proven himself to be a helpful utility player when needed over the past couple of years, although you would not want him playing every week. But for a game like this, at a time like this, Solskjaer needs a reliable pair of hands.
Rojo, on the other hand, feels far more chaotic, prone to moments of madness or confusion. He is also not a left-back. He really is not a left-back. Jose Mourinho played him there for 45 minutes against Valencia in December and promptly hooked him off at half-time.
No, for a game like this – one harder than it looks – Solskjaer needs a player who can stick to the job. Darmian just about offers that. Rojo does not.