Jose Mourinho has described Manchester United boss Louis Van Gaal as an ‘important’ influence on his career and believes the Dutchman can rebuild the Old Trafford empire.
Mourinho was one of Van Gaal’s assistants during his time as manager of Barcelona in the 1990s and the two became close friends.
Sunday will pit the pair against each other for only the second time, the only other meeting won by Mourinho’s Inter Milan in the 2010 Champions League final with Bayern Munich.
Despite Van Gaal’s new side trailing the Blues in the standings, Mourinho thinks his old pal is in a great position to return the glory days to the Red Devils.
Mourinho said: "Man United is Man United. For me it doesn't matter the manager, the moment, the table, the players. Man Utd is Man Utd and I always look at them independent of these factors.
“I think they [United] are in a fantastic position. You are in a difficult position when you have not the funds to rebuild a team. When you have the funds you have to buy well and you have to coach them well. I know Louis is capable to buy well and is capable coach them well. Let’s see how things end at the end of the season. It’s too early.
“What's important is that I don't play against Louis Van Gaal. It's Chelsea against Man United . During the match I have no time and he has no time to look around and see who opposing manager is. Before and after he's one of my big friends and I will always be happy to see him.
"He was important. He gave me a good opportunity to work at a high level. As a young coach to be working four consecutive years, one with Mr (Bobby) Robson and three with Louis in club like Barcelona was very important. If I had to choose important people in my career for sure he's one.”
Van Gaal had his own injury concerns over record signing Angel Di Maria but has confirmed the Argentine will play at Old Trafford, with the United boss expecting to see Costa line up for the Blues come Sunday.
"I think Costa will play," said Van Gaal. "I think he can play maybe because I have read on the websites that he has trained this week. I also have my eyes open.
"He has scored nine out of seven which is remarkable. He is in good shape but he was ill yesterday.
“They [Chelsea] are one of the top and so is Man City and Jose has worked more than one year with his team and he didn’t win any prizes.
"You have to build up and playing like a team. I want my teams to do that. Play like a team for 90 minutes. We did that I think vs West Brom, but we made individual errors."