Following the disastrous tenure of David Moyes in 2013-14, United turned to Louis van Gaal in the close-season in the hope the Dutchman could return the club to winning ways.
Van Gaal brought the likes of Angel Di Maria and Radamel Falcao to Old Trafford as United's transfer dealings dominated the headlines during the window, but early results have been inconsistent despite the high-profile arrivals.
With Premier League leaders Chelsea visiting on Sunday, Mourinho has dismissed the notion that United are struggling.
"Man United are in a fantastic position," he said. "You are in a difficult position when you don't have the funds to be behind the rebuilding of a team.
"When you have the funds you have to buy well and coach them well, and I know Louis is capable of buying and coaching them well so they are fine.
"But we are very confident about ourselves. I am not interested in thinking which team Man United are going to play, who is playing and who isn't playing."
The fitness of Diego Costa has been a running theme ever since the former Atletico Madrid forward moved to Stamford Bridge, but Mourinho will not hold the striker back if he proves his fitness.
"I don't protect players before a Man United game, unless he cannot play," he said.
"If there is a chance of playing, Old Trafford is not the place to protect players, it is the place to put the players who want to play and are ready to play. If Diego is ready to play, he plays."
