Crisis-hit Manchester City slumped to an unthinkable ninth defeat in 12 matches at Aston Villa on Saturday as Nottingham Forest stormed Brentford's fortress to climb to third in the Premier League table.
Alexander Isak scored his first hat-trick in the English top flight as Newcastle ran riot at Ipswich while West Ham and Brighton shared the spoils at the London Stadium.
City boss Pep Guardiola -- in the worst spell of his managerial career -- made multiple changes following last week's painful derby defeat to Manchester United but it was to no avail as his injury-hit side lost 2-1.
Jhon Duran scored his seventh Premier League goal of the season to put Villa ahead in the 16th minute and Morgan Rogers doubled the advantage for the impressive home side in the 65th minute.
Phil Foden scored his first top-flight goal of the season in stoppage time to pull one back but it proved to be too little too late for the flailing champions, whose spark has vanished.
City have now lost six Premier League games in the current campaign, twice as many as they suffered during the whole of last season, when they were crowned champions for a fourth straight season.
They are realistically out of the title race already -- nine points behind leaders Liverpool having played two games more, while Villa leapfrogged them into fifth spot.
Guardiola said he trusted his players to turn things around despite their shocking run of just one win from their past 12 games in all competitions.
"It depends on us," he told the BBC. "The solution is bring the players back. We have just one central defender fit, that is difficult."
"We have to think positive and I have incredible trust in the guys," he added. "Some of them have incredible pride and desire to do it. We have to find a way, step by step, sooner or later to find a way back."
Villa boss Unai Emery told TNT Sports that Villa were "feeling strong".
"We played the first half very well," he said. "In the second half we kept possession more and getting in the box to score the second goal, we imposed and dominated more."
Isak hat-trick
Forest won their third consecutive Premier League match to keep up their push for European football, condemning Brentford to their first home defeat this season.
Coming into the game, Thomas Frank's team boasted the best home record in the league, with seven wins and a draw from their eight games at the Gtech Community Stadium.
But they came unstuck against Nuno Espirito Santo's in-form team.
Ola Aina slotted home the opener towards the end of the first half and Anthony Elanga made it 2-0 early in the second period.
"It's about enjoying the moment," said Nuno. "It's a very hard competition. Every game is so difficult and the next one is going to be very tough.
"We're very proud of all the things we've been able to achieve, but we've achieved nothing yet."
Arsenal will reclaim third spot in the table if they take at least a point from their match against Crystal Palace later on Saturday -- a day after Mikel Arteta celebrated his fifth anniversary at the club.
Newcastle deepened Ipswich's plight and lifted themselves to seventh in the table with a 4-0 win at Portman Road.
Isak volleyed Eddie Howe's team ahead in the first minute and Jacob Murphy doubled their lead before Isak side-footed in from close range just before the break.
The Sweden international scored his third nine minutes into the second half, poking the ball home after more fine work from Murphy.
It was a ninth defeat in 17 games for Ipswich since they returned to the Premier League and they remain in the relegation zone, two points from safety.
Mats Wieffer gave Brighton a 51st-minute lead against West Ham but Mohammed Kudus equalised seven minutes later and the match finished 1-1.
Premier League leaders Liverpool face a tricky trip to Tottenham on Sunday while second-placed Chelsea visit Everton among five matches.
Away from Saturday's action, Premier League basement club Southampton named former Roma and Torino boss Ivan Juric as their new manager, replacing the sacked Russell Martin.