Henrikh Mkhitaryan made his first Manchester United appearance since September 10 in the Europa League defeat to Fenerbahce - but has been warned that he must do better by Jose Mourinho.
The £24million summer signing from Borussia Dortmund ended his 54-day exile as a second-half substitute during United's loss in Turkey.
Mourinho accused his players of treating the match like a "summer friendly" having fallen behind after just 65 seconds to Moussa Sow's goal, before Jeremain Lens doubled the hosts lead in the second half.
But he also had further words of caution for Mkhitaryan, who hadn't appeared for the Red Devils in 11 matches, since being hauled off at half-time in the Manchester derby.
"He has to do more, it is as simple as that," said Mourinho.
"We have big expectations in the club. We have lots of players for these positions and he has to play better than [Juan] Mata, he has to play better than [Jesse] Lingard, he has to play better than [Anthony] Martial.
"He has to play better than them. It is as simple as that.
"Every manager in the world wants to win matches. Every manager in the world wants to play the players he thinks can help the team more and I am no different."
In pictures - Fenerbahce 2-1 Manchester United:
Mkhitaryan's return to action came after he had again been overlooked for the squad in the 0-0 stalemate against Burnley at the weekend.
He and the rest of the squad travelled back to England immediately after their loss in Istanbul, arriving back at Manchester airport at 3.30am, to begin preparations for their meeting with Swansea on Sunday.
Mourinho will serve a one-match touchline ban at the Liberty Stadium, after being hit by the FA with a misconduct charge and admitting using abusive/and or insulting words during a tunnel bust-up with Mark Clattenburg on at Old Trafford on Saturday.
However, the Portuguese will be allowed to give his pre-match team talk in the dressing room before the game, while also being allowed to share messages with the United bench.
Yet he was left furious with his players in Turkey, believing that they ignored his advice.
"What disappointed me more is that I have quite a big experience of playing against Turkish teams," Mourinho said. "I played twice with Real Madrid and twice with Chelsea, I played with Porto too, so I pass to the players all my experience.
"And my experience is that when you play against them in our home, it's easy. It's always 2-0, 3-0, 4-0, it's easy.
"You come to Turkey and it is completely different story, so I told them to wait for that, told them not to be focused on the easy game we had at Old Trafford and to be ready for a completely different game.
"We started the game sleeping."
