The Red Devils slumped to a 3-0 home defeat to Tottenham, once again raising questions over Mourinho’s future at the club.
After a goalless first half, Harry Kane broke the deadlock when he headed home Kieran Trippier’s corner shortly after the break.
Just minutes later Lucas Moura doubled the visitor’s lead giving United a massive hill to climb.
However, Mourinho’s side were unable to find a way back into the game and Moura put the clash out of reach six minutes from time when he netted his second of the evening.
The defeat, their second in three games, means Manchester United have suffered their worst start to a Premier League season since 1992.
“Anyone who watched this game, one thing they know for sure is the team is united,” Mourinho told Sky Sports.
“The boys don’t give everything they gave if the team isn’t united.
“I think it’s the time to stop with untruths.
“The solidarity to play together for United and lose at home is hard for everyone, but the team is united.
“There is no union without the manager.”
The under-fire boss admitted that he didn’t know where it went wrong for his side this evening.
“I don’t know (where it went wrong),” he said.
“Goals are an amazing vitamin and goals conceded are an overdose of fatigue.
“We arrived at half-time wondering why we were not winning, and then conceding two quick goals was an overdose of fatigue.”