The first half was one of casual but fairly flat dominance from the home side, as United saw much of the ball but couldn't create any clear chances. Cluj had clearly come out with intent, and their pressing began to wreak havoc on United's nervy backline as the visitors looked to steal possession. It was no surprise to see the best chance on goal come from a United error, with Scott Wootton giving the ball away to Sougou, although the United youngster recovered to deflect his shot behind.
Shortly afterwards, United almost took the lead when Welbeck played Tom Cleverley into space, but the youngster's touch was poor and the chance was gone as the Cluj goalkeeper came out to claim the ball. United enjoyed a second chance later as they showed their newfound danger from corners, Rooney's delivery met by Welbeck, who forced a fine save from Felgueiras.
Chris Smalling was probably playing for his place against Manchester City at the weekend, but he let himself down just before half-time with a bad miss. First Felgueiras tipped a Wayne Rooney lob away, before a returning cross found Smalling unmarked at the back post, but the defender sent a poor header wide.
The half-time whistle heralded bad news for United as, although they had little investment in the outcome of the game, Tom Cleverley was withdrawn due to injury, Paul Scholes replacing him. The youngster will now surely be a doubt against Manchester City and adds to United's midfield injury woes.
The second half continued in much the same way as the first. Nick Powell, United's best player by a distance, did well to pick out Rooney with a fine pass, but the striker misplaced his cut-back, allowing a Cluj defender to get bac and deal with it.
Despite United continuing to look threatening, on 56 minutes, it was the visitors who took an unlikely lead. Paul Scholes uncharacteristically surrendered possession tamely before characteristically going in with a kamikaze challenge which completely missed the ball but fortunately for all concerned also the man. Luis Alberto then received the ball in the now-abandoned hole, and with no United player anywhere near him, had time to pick his spot, sending a scorcher flying into the top corner of the net.
There was a moment of rage and comedy from both sides shortly afterwards as Rui Pedro lost possession to Ryan Giggs and who went down apparently injured. United refused to half play, going up the other end with the Welshman almost getting the ball in the Cluj net - cue much yelling and shoving from Cluj, much yelling and shoving from United in response, and Rui Pedro getting up entirely unharmed, much to the ire of the home crowd.
United have gone behind in 65% of their games this season. Many of those they have stormed back to win, but that was not the case tonight as they looked worse after going behind, incapable of forcing a chance from the Romanians. In the end, Cluj were done for thanks to events elsewhere, Galatasaray taking the lead in Braga to condemn them to the Europa League regardless of their incredible victory. United were awful on a flat, emotionally-dead night at Old Trafford, but they could afford to be, with the focus very much on the weekend. Cluj will be desolate at having achieved such a victory but going out regardless, but with the club not having been expected to even qualify for the Europa League, they can be pleased with themselves.