Manchester United clinched all 3 issues in opposition to Southampton due to Romelu Lukaku’s strike on 20 mins.
But the Red Devils had been left protecting on in the second one part, with Mourinho admitting his facet struggled fitness-wise at St Mary’s because of the 19°C heat.
“I think they were really tired at the end,” Mourinho stated in his post-match press convention.
“Nine of them did not play in midweek, so 9 of them it is not even an accumulation of fatigue. I feel the elements was once stunning.
“Even when you teach at 11am, 12pm, 3pm in Manchester, we do not get this climate. Seriously.
“The closing time we had this was once in Los Angeles [for preseason] after which in Macedonia [for the Uefa Super Cup], and I feel they felt it.
“I noticed some gamers no longer sharp. Great spirit and all the time making an attempt, however no longer the similar sharpness.
“So in case your opponent is coming with the whole thing in opposition to you, let’s do it for 10 or 15 mins and keep cast.”