It was just as well, then, that he only had to wait three days.
The Armenian scored the game's only goal Sunday to give his side, and coach Jose Mourinho, a much-needed win over Tottenham Hotspur.
Without a victory in the league since traveling to Swansea on November 6, United had fallen well off the pace set by title-chasing Chelsea and were in danger of losing touch with the top four.
But a blistering run and emphatic finish from summer signing Mkhitaryan ensured Mourinho's men move to within six points of Manchester City after Saturday's defeat to Leicester.
Mourinho has come in for some criticism of his treatment of Mkhitaryan since his arrival at the club, leaving him out of the majority of match day squads and publicly questioning his ability to adapt to the Premier League.
But the Portuguese was full of praise for the 27-year-old after his second straight man of the match performance.
"We scored a fantastic goal and it was so important for us in the end," Mourinho told Manchester United TV.
"The goalkeeper [Hugo Lloris] was not the Man of the Match, because Mkhitaryan deserved that, but he could have been too... and also the post!
"For the way we play, we don't deserve to suffer, we don't deserve to arrive in the last 30 minutes with our hearts in our hands. We deserved to be enjoying the match and we cannot enjoy the match when we are under pressure."
However, it was a bittersweet day for Mkhitaryan who was stretchered off injured in the dying minutes after twisting his ankle in a challenge with Danny Rose.
Initial observations, Mourinho said, indicate he will only be out for up to two weeks and could return for United's boxing day fixture against Sunderland.
Best of the rest
Liverpool's stuttering title charge took another blow Sunday as it was held to a 2-2 draw at home to West Ham.
After dropping three points in a thrilling clash against Bournemouth last weekend, manager Jurgen Klopp was looking for a positive response from his player in front of their own fans.
Goalkeeper Loris Karius -- who was criticized for his error which led to Bournemouth's winner -- was again at fault for allowing Dimitri Payet's weak free-kick to squirm into the corner, after Adam Lallana had given Liverpool the lead.
A defensive error from Joel Matip then allowed Michail Antonio to prod the ball past Karius to put West Ham in front, before a goalkeeping error from Darren Randolph gifted Divock Origi an equalizer.
Klopp, however, refused to blame his players for a further two dropped points.
"The first goal was a wonderful free-kick and the second was an unlucky," the German told Sky Sports. "We shouldn't have lost the ball before we made the foul for the free-kick.
"The passes played were deflected and Joel, who played a fantastic game, couldn't clear the ball and then Loris was surprised like everybody. We scored a wonderful goal and created plenty of offensive situations - we should have had more."
"I'm pretty sure we could have had one or two penalties given. We have to take it. It felt like we was in their box for the whole game but it's not that simple. It's all about making the right decisions and you need a little bit of luck.
"A draw doesn't feel too good, but it doesn't feel too bad either."
The draw means Liverpool drops six points behind leader Chelsea, which has a solitary Diego Costa goal to thank for a hard-fought win against West Brom.
Arsenal kept up the pressure on its London rival after coming from behind to beat Stoke Saturday, while Manchester City's leaky defense conceded four goals as reigning champion Leicester looked to kick start its season.