Mourinho has made a confession that he surprisingly got emotional after Rooney’s departure for Everton, and he already misses his former captain.
The 31-year old forward made his return to Everton earlier this month, ending a trophy-laden 13-season stay at Old Trafford.
United and England’s all-time leading goalscorer, Rooney made just 15 Premier League starts in 2016-17.
But Mourinho is already missing the forward and said he would be tough to replace.
“I miss him a lot, I miss the guy a lot, I think he’s a fantastic guy,” the Portuguese tactician said, via The Telegraph.
“I’m not the kind of guy that gets normally emotional in my job and I did it with him when he left, but I am sure that he’s going to be very good for Everton, and Everton is going to be very good for him.
“Wayne was a very positive influence. We cannot say we are going to improve the group because Wayne left. No way, or the other way around.
“He was such an important guy and a good guy for us. I just think it is a new period without that face, without that leader, without that good influence on us.”
Indeed, Rooney is already proving his stuff with Everton; scoring two goals in as many preseason friendly games.