After one week of training in his second spell as Blues boss, Mourinho expressed satisfaction at his players' work ethic and branded speculation surrounding Rooney's future - as well as that of Aston Villa's Christian Benteke - as "rumours".
Mourinho named two sides for Wednesday's first match of his return, the pre-season contest with Singha All-Stars in Bangkok, and appears set to begin with the same four-two-three-one formation favoured by predecessor Rafael Benitez and which delivered the Europa League trophy in May.
The 'Special One', who returned to Stamford Bridge last month after a near six-year absence, hopes for victory at the Rajamangala Stadium on Wednesday.
"Winning is part of a culture: if you can do that even in friendly matches, we have to do it," he said. "I don't like to lose, the players don't like to lose.
"They are competing fantastically in training sessions, and against several players, so my boys will try and get a result.
"To lose is not a drama. It doesn't change anything in the teams. But it's not nice. We don't like that.
"It's not the most important thing to get a result, but we want to win."
Manchester United lost to Singha All-Stars in Bangkok last weekend and were without Rooney, the striker returning home with a hamstring injury as Chelsea arrived in Thailand.
Rooney is among the players linked with a move to Stamford Bridge in recent weeks and Mourinho has expressed his admiration for the striker.
The Portuguese coach, however, insists he is pleased with the make-up of his squad, with 25 players at his disposal in Bangkok, plus those who were involved in the Confederations Cup that are still to return to club duty.
"At this moment I'm so happy with the people I have here that I'm not thinking about other players," Mourinho added.
"If I have to think about some players, I have to think about my players who are on holiday period and still have to join us on July 28.
"The first part of my job is to get the best from these players, try to push the young boys to the levels they can reach, and to try to make a real team. After that, we will see.
"This is a period where the big clubs, and the managers of the big clubs, are connected with every player.
"Until August 31 (and the close of the transfer window), that's the old story in football. Rumours and rumours and rumours.
"At the end of the day, after so many rumours, some things come true.
"Until August 31 we will see if anyone can improve our squad, but my focus and ambition is to work with these guys."
After a successful but ultimately acrimonious spell at Real Madrid, Mourinho is revelling in his return to Chelsea.
"After a week I'm still the 'Happy One' because my boys work fantastically," he said.
Chelsea have been partaking in twice-daily training sessions in preparation for the forthcoming season and while insisting his side have "no priorities" in terms of competitions, it is clear Mourinho would like to win the club's first Barclays Premier League title since 2010.
Mourinho, who in 2005 guided Chelsea to a first championship in 50 years, said: "A competition like the Premier League the best team wins. The best way to work is to try to be the best team.
"It's a championship in European football where we have more candidates to win, so because of that it's more difficult to win.
"Both teams in Manchester are top teams - the last two champions of the Premier League - Liverpool are coming up with Brendan (Rodgers), Tottenham are a fantastic team with some new players for sure and Andre (Villas-Boas) will also have a fantastic team, Arsenal the same.
"But we want to be there and we'll be fighting for that."
The internal competition at Chelsea will be evident on Wednesday night when Mourinho fields a first-half team of: Petr Cech, Wallace, Tomas Kalas, John Terry, Ashley Cole, Frank Lampard, Michael Essien, Lucas Piazon, Kevin de Bruyne, Andre Schurrle and Romelu Lukaku.
De Bruyne will be the only member of the starting XI to begin the second half, with Jamal Blackman, Branislav Ivanovic, Gary Cahill, Nathaniel Chalobah, Ryan Bertrand, Marco van Ginkel, Ramires, Eden Hazard, Demba Ba and Victor Moses joining him.
"They know that if they can work hard for three hours a day, tomorrow instead of three hours a day I'm only asking them to work for 45 minutes, so they have to give a strong performance," Mourinho said.