"At the final whistle as well, the way they were clapping the team was I think really respectful and really nice for us as players to receive after a disappointing result". Their defence is failing after three Premier League games, following a season in which the Red Devils conceded 28 goals in 38 games, behind only Manchester City on 27.
"They have the quality, they just have to keep pushing", former Manchester United and England worldwide Rooney told CNN Sport's Patrick Snell.
Two goals in the space of three minutes rocked the hosts and Lucas Moura's second goal then killed off any hope of a comeback.
Next up for is a potentially tricky away trip to Burnley, as the club's shocking transfer window transfers into their regular season.
The England striker sent a looping header into the top corner five minutes into the second half at Old Trafford, following a tightly contested opening period.
"I need to know what's the most important thing", Mourinho asked reporters on Monday, "if it is to play well or win matches?"
The Portuguese last week said had "no problem" with United executive vice-chairman Ed Woodward, amid reports that they have fallen out. The only defensive arrival was young Diogo Dalot, who is a full-back, while he was joined by Fred and back-up goalkeeper Lee Grant. This (holding three fingers up). After beating Leicester in its opener, United lost to Brighton 3-2 and now has three points after three rounds. The players are already talking about the possibility of Zidane coming in'.More news: Camila Cabello Wins Video of the Year at MTV VMAs 2018!
One win and two defeats. It's early in the season and we've got a lot of game to come.
"Manchester United are not just about winning".
The pressure on Mourinho is mounting fast, with United having slumped to 13th place in the table.
Mourinho's relationship with key players appears fractured.
A surprise 3-2 defeat to Brighton, who are expected to be in the mix for relegation, put United into a precarious position.
After scoring his first goal at Old Trafford, Kane told Sky Sports: "That's massive, to come here and win the way we did is a big statement". We haven't started well in previous years, we've dropped points here and there and then we've had to play catch-up for the rest of the season. "It is about him giving the best that he has".
United return to action on Sunday when they travel to Turf Moor to face Burnley, one of seven teams now below them at this early stage of the Premier League season. "We have crated many opportunities, as in most of our matches, so I feel frustrated", Mourinho said.