Bernardo Silva said Manchester City "played like under-15s" in the closing stages against Manchester United after the out-of-form Premier League champions slumped to a dismal 2-1 derby defeat on Sunday.

City appeared to be limping towards a much-needed victory at the Etihad Stadium before a calamity of errors late on, with Bruno Fernandes scoring a penalty in the 88th minute before a stoppage-time winner from Amad Diallo.

Both goals were a result of sloppy defending from City, particularly the opener after Matheus Nunes gave the ball away before chopping down Diallo in the box.

The defeat means City have won only one of their past 11 games in all competitions, continuing the club's worst run of form since 2006.

"We deserved what happened," Silva told Sky Sports. "At this level, a game or two is unlucky. We can't say this is lucky or unlucky -- 10 games, it's not about that.

"Minute 87 in a derby, winning 1-0 and our corner ends in a penalty for them, if we make these stupid decisions with three or four minutes to go, you deserve to pay for that. Looking at the game, I think there was only one team that could win the game, but at the end we lost.

"It's not one game; it's a lot of games lately. We have to look at ourselves. You can't say oh it's a bit unlucky, no. It's the decisions you make. Today in the last minute, we played like under-15s."

Silva added: "It's quite normal that we're not very happy at the minute. Not just this game, but the last month. We have to do better individually and collectively because it's not the standards of Manchester City."

Fellow midfielder Phil Foden was similarly dismayed as City -- who have the lowest points-per-game in the entire league since the beginning of November -- fell to an "unacceptable" loss. The Englishman also suggested City's problem was a "mental thing."

"Massively [disappointed] -- the game was in our hands," he told the BBC. "We were 1-0 up and controlling the game. We had a lot of possession. Seems to be the story at the moment. I don't know what happens but we switch off and they score two goals.

"It keeps happening at the moment. We have to stick together now, rebuild and go again.

"You can concede at 1-1 but you can't concede straight after, that's unacceptable.

"At the start when you lose a couple of games [it's not a mentality problem] but when it happens a lot it feels like a mental thing. We need to get out of that and get back to winning ways and pick ourselves back up."