MANCHESTER, England — As Manchester United’s goals flew in at Old Trafford, Wayne Rooney could only applaud from the substitutes’ bench.

He might have to get used to his new role as a bystander.

Rooney was dropped for the English Premier League game against champion Leicester on Saturday in Jose Mourinho’s biggest call in his short time in charge at Old Trafford. It proved a good decision, with United winning 4-1 and Rooney’s replacement at No. 10 — Juan Mata — scoring.

Mourinho said Friday that his captain had not been the same player since he was criticized for his display for England against Slovakia in a World Cup qualifier in early September.

Aside from being occasionally rested, Rooney has not been dropped by United since he was left out by Louis van Gaal against Stoke midway through last season. Before that, he was also dropped for the last three games of Alex Ferguson’s long reign in the 2012-13 season after falling out with the then-United manager.

The 30-year-old Rooney has scored one goal in eight games for club and country this season.

“My captain is my captain,” Mourinho said. “If he is on the pitch, if he is at home, he is my captain. It’s not a problem.”

Mourinho said it was a tactical decision to drop Rooney, rather than a reflection on his form.

“We thought today the way they defend, the profile of their defenders, we thought the best solution for us was to play with the two fast kids (wingers Marcus Rashford and Jesse Lingard) and with Mata in a position where he can interact with these young kids,” Mourinho said. “It went well for us.”

Mourinho said in his first news conference as United manager that he will only play Rooney as a center-forward or as a deep-lying forward. Rooney faces strong competition in those areas, with Zlatan Ibrahimovic and Rashford preferred as striker and Henrikh Mkhitaryan, Paul Pogba and Mata as options in the No. 10 role.

The England striker came on after 83 minutes to applause and played on the left wing.

“You prefer always to ask why somebody is not playing,” Mourinho said. “Sometimes when I read you (in the media), I feel I know nothing about football. But there is one thing I know — the rules of the game. And I can only start with 11, until somebody tells me there is a change in that.”

Rooney has struggled for form in United’s recent games, with critics saying he has lost pace and explosiveness and slows down the team’s attacking tempo.

On Friday, Mourinho made a direct correlation between Rooney’s poor form and perceived media criticism the striker received after his England performance on Sept. 4 against Slovakia. England won that game 1-0.

“Honestly,” Mourinho said, “I think there was a Wayne before the Slovakia-England and a Wayne after Slovakia-England.”

Rooney is England’s record scorer on 53 goals. He has also scored 246 times for United and needs four more goals to surpass Bobby Charlton as the club’s record scorer.