The Gunners suffered a 2-0 defeat at the hands of Tottenham Hotspur on 30 April in their last fixture. The Red Devils, on the other hand, managed a 1-0 win over Celta Vigo in the first leg of the Europa League semi-final in Spain on 4 May.
United, who played nine matches across all competitions in April, will have less time to prepare for the clash against Arsenal, when compared to that with the north London club. They won the EFL Cup in February after defeating Southampton and are the firm position to qualify for the final of the Europa League.
Mourinho earlier admitted that he would consider fielding a weakened team to face Arsenal. United are struggling with injuries since the last international break after the Portuguese tactician blamed the fixture pile up as one of the main reasons for the majority of the injuries. Wenger has explained his United counterpart as to why should be happy with the fixture congestion.
"Normally a hectic schedule is what you want and that shows that you are in all the competitions. Overall I must say that if you have no big injuries we are all equipped now in the Premier League to deal with that," Wenger explained, as quoted by Arsenal's official website.
"What has changed in the Premier League is that if you look at the benches between the teams that are between 10th and 20th, there are still top players on the bench at every single club.
The Old Trafford club have played 58 matches across all competitions so far this season. United will play five matches in the space of two weeks, starting from the clash against Arsenal.
United's trip to the Emirates is sandwiched between the two legs of the Europa League semi-final clash against Celta Vigo. The second leg will be played at Old Trafford on 11 May, just days before the Red Devils' league clash against Tottenham Hotspur.