Manchester United still sit three points clear at the top of Group A in the Champions League, but they could have wrapped up the group with a win in Switzerland last night.
Thanks to a late effort from Michael Lang, Basel emerged with a 1-0 victory over Jose Mourinho's side and gave themselves a terrific chance of progressing to the knockout stages of the competition.
United had their chances with £75 million man Romelu Lukaku missing a particularly good one-one-one opportunity, and, as Mourinho said after the game, United could have been 5-0 ahead at half-time.
However, that wasn't to be the case and the Red Devils were made to rue their missed chances late in the day.
United should still finish top of the group if they avoid a heavy defeat to CSKA Moscow at Old Trafford in two weeks time, but Mourinho was clearly frustrated with only the club's third loss of the season on Wednesday.
So, what was to blame for United's demise? Injuries? The referee? The players? Believe it or not, Mourinho blame himself.
"The first-half was a perfect half without the goals," Mourinho said. "Was perfect, the first-half was perfect, was difficult to repeat in the second-half, we knew that the opponent would try a different reaction.
"Did Paul Pogba come out have an impact in the team? I think it had, we were not such a good team after Paul had to come out but he had to be, he cannot go to levels of fatigue after 65 minutes."
Mourinho accepts that by withdrawing Pogba, United's play dramatically declined. However, he went on to suggest that with the calibre of players he had on his bench, they should have got the job done - but he still said he couldn't blame the players.
"But, I brought to the pitch an experienced player like Matic that I thought could effect the game, I bring Marcus [Rashford] to give us more depth, more speed, more problems, Zlatan to hold the ball, to sit with the ball, to drop and have it.
"The approach was good, I cannot blame the players, I think we play a match like this 10 times and out of nine we win comfortably. The one was now."
United now move on to Brighton on Saturday looking to cut the gap on runaway Premier League leaders and close rivals Manchester City.