Maintaining an unbeaten personal record against Wenger's Arsenal in the league until last May, it was his arrival and Abramovich's riches that heralded a change the Frenchman struggled to keep the pace with. Instead, Antoine Griezmann found a pivotal away goal that leaves Arsene Wenger's men in trouble of falling short.
Mourinho could name an unchanged team to the one that beat Tottenham in the FA Cup semi-final last weekend.
In many respects, the match feels a little insignificant here.
As well as Elneny making an appearance, Henrikh Mkhitaryan - who has not played since picking up an injury against CSKA Moscow - took part in full training and is in contention to play against his old club United on Sunday. "When I look back now I realise what a great team they had", Wenger said of United.
Mourinho memorably called Wenger a "specialist in failure" in 2014, when he was the Chelsea manager.More news: Dow Jones falls over 420 points
Their verbal warfare nearly spilt over into fisticuffs in 2014 when Wenger and Mourinho clashed during Chelsea's 2-0 win over Arsenal at Stamford Bridge. A win will guarantee the hosts qualification for next season's Champions League.
"They pushed us to the limit, the two matches we played, not at the Emirates (Stadium), but at the unbelievable old stadium (Highbury), unforgettable".
However, ahead of United's game with Arsenal at Old Trafford, Mourinho says he respects Wenger and he hopes they can be friends in the future. We had big matches, big fights, so thank you so much for that. "I have never been an entire season without victories, so that means that if I don't win the FA Cup, the fact that I made it to the finals turns into only an "option". "I turned many, many, many clubs down to face the challenge when we built the stadium", said Wenger, referring to the Emirates. We were not good enough to win it.
Mourinho also said there was "no chance" that keeper David de Gea would be allowed to leave the club in the close season.
After 22 years with the Gunners, Wenger will depart at the end of the season.