Mkhitaryan has started all six of Manchester United's Premier League games this season and has been in brilliant form for Mourinho's men, making five assists and scoring one goal.
"This season is another season and we need him to perform well again".
The Red Devils take on CSKA Moscow in Russian Federation on Wednesday and will have less than 72 hours to prepare for their 3pm kick-off against Crystal Palace on Saturday at Old Trafford.
In fact, the Red Devils have a total of 196 hours respite between Champions League away games and their next Premier League fixture. Champions League is a different level and the quality is higher, difficulties are higher.
Yet Liverpool's Champions League away match with Maribor on Tuesday 17 October is followed by a 4pm Sunday kick off at Tottenham - 114 hours apart - and their visit to Sevilla in November is also on a Tuesday and followed by 5.30pm Saturday kick-off at home to Chelsea, which means 92 hours respite.
He said at the time: "We have lots of enemies, it is hard to play Monday night, it is hard to play Monday night with 10 men".
The Portuguese boss was angered at the Premier League's lack of help throughout his side's Europa League campaign last season when the Red Devils often had Sunday clashes after a Thursday night game in Europe.