Sub-plots: The Reds could be on the brink of sealing qualification in the competition, which would allow Sir Alex to rotate his squad for the final two group matches. With the final European fixture of the year, at home to CFR Cluj, coming a matter of days before the big Manchester derby at the Etihad Stadium, resting some weary legs could prove important in terms of the battle for the title.
Whistle blower: German Florian Meyer is Wednesday's referee. The only other match he has taken charge of in this term's Champions League was also in Portugal as Benfica met Spartak Moscow, but he has plenty of experience and was the fourth official between the topsy-turvy 2007 Champions League final between AC Milan and Liverpool. The 43-year-old has only ever sent one player off in the competition. Fenerbahce's Claudio Maldonado received a red card in the final minute of a 2008 tie away to Dynamo Kiev.
Rivals watch: Galatasaray travel to CFR Cluj in the other match in United's group. Elsewhere, Chelsea face Shakhtar Donetsk at Stamford Bridge and Celtic welcome Barcelona to Parkhead as the last round of games are reversed with a number of potentially entertaining ties taking place across Europe.