Phil Foden's hat-trick consigned Brentford to a 3-1 defeat to Manchester City on Monday night.
Neal Maupay's cool one-on-one finish, which was the striker's fifth goal in as many games, gave the Bees the lead on 21 minutes.
But a Foden goal before half-time and two more after the break secured the victory for Pep Guardiola's side at Gtech Community Stadium.
Maupay's composed finish gives Brentford the lead
Thomas Frank made just one change to the side that lost 3-2 to Tottenham Hotspur last Wednesday, as Sergio Reguilón made his first start for the club, replacing Keane Lewis-Potter in the starting XI.
Manchester City make four changes following their 3-1 victory over Burnley last week, with Kyle Walker, Rúben Dias, Bernardo Silva and, notably, talisman Erling Haaland coming in for Rico Lewis, Stones, Matheus Nunes and Jérémy Doku.
Brentford created the first chance of the game, when a counter attack involving Toney first saw Maupay robbed in the box, before the centre-forward got the ball back. His second cross was a dangerous one, and was scrambled away by Dias.
Álvarez took aim for City with 10 minutes gone, as the visitors began to turn the screw. The Argentinian, who netted twice in the win over Burnley, fired from the edge of the area, but Flekken dived to his left and parried it around the post.
Flekken was being kept busy by City throughout the opening quarter of an hour, as he got down low to save Álvarez's second attempt of the game, before he dived the same way to tip Kyle Walker's ferocious effort out for a corner.
Despite City dominating the chances and possession, Brentford took the lead. A Flekken goal kick was pumped forward and, as Toney left it, Maupay took the initiative and cooly slotted home when faced one-on-one with Ederson.
An almost identical chance occurred at the other end - but Flekken ensured it was a different result. A back pass by Vitaly Janelt was intercepted by Haaland, but the centre-forward's effort was stopped by the stretched legs of the Dutch keeper.
Flekken was at it again, with Gvardiol the latest to shoot from distance. But, once more, the Bees' no.1 kept him out.
There was nothing he could do on the stroke of half-time, however, when Foden produced the leveller. Ethan Pinnock didn't generate enough power on his defensive header from Kevin De Bruyne's cross, and the England international was first to the loose ball to poke home from close range.
Foden strikes twice more after the break as battling Bees fall to defeat
The second half started with City bossing possession and territory - and, on 53 minutes, they took the lead.
De Bruyne whipped a perfectly weighted cross into Phil Foden and, after the midfielder ghosted between Pinnock and Reguilon inside the six-yard box, he headed into the bottom corner.
The Bees fought back, and a terrific ball from Reguilón found his full-back partner Roerslev on the other side of the pitch, who hit a sliced effort just wide.
Nørgaard was then at the heart of a great move and chance for the hosts. A loose ball was picked up by the Dane and fed out to Reguilón; another great delivery from the Spaniard found Toney at the back post, who hooked back to Nørgaard from the byline, but his shot was blocked by a diving Dias.
Toney had a chance of his own moments later, when a cross was played into him by Maupay just inside the area, but he couldn't keep his acrobatic effort down.
And City went on to increase their advantage with 70 minutes on the clock. Some cute football on the edge of the area saw Haaland and Foden combine, before the latter neatly finished to complete his hat-trick.
Brentford: Flekken, Collins, Pinnock, Mee, Roerslev (Lewis-Potter 77), Jensen (Damsgaard 77), Nørgaard, Janelt (Yarmoliuk 77), Reguilón (Ajer 79), Maupay (Baptiste 90+5), Toney
Subs not used: Strakosha, Zanka, Fredrick, Brierley
Manchester City: Ederson, Walker, Dias, Aké, Gvardiol, Rodri, Foden, De Bruyne, Álvarez, Silva (Doku 71), Haaland (Kovacic 86)
Subs not used: Ortega, Lewis, Stones, Akanji, Nunes, Grealish, Bobb
Attendance: 17,096
Frank on Brentford's performance against 'best in the world' City
Discussing his side's performance, head coach Thomas Frank believes Phil Foden's equaliser on the brink of stoppage-time was disappointingly the turning point of the game at the Gtech on Monday night.
“Overall, it was a good performance against a very, very good team, probably the best in the world," said the Brentford boss.
“We did so many things right, I want to praise the players for that. Of course, we need to look into the three goals we conceded - they were against a good team that put us under constant pressure.
“But we were brave, we defended well in long spells, and it's close to being a very good first half but, unfortunately, we give that goal away. If only we could have held out until half-time, we could’ve got a little bit more, but, hey, that happens.
“We came out second half, continued well, then we conceded the 2-1, where we knew we had to close down [Kevin] De Bruyne and, unfortunately, we didn't do that.
“So those two goals, and the chances to Ivan [Toney] and Christian [Nørgaard], was the difference between the two teams, on a day where we faced them and we needed to be almost perfect.”
Flekken: I’ve found my place at Brentford
Goalkeeper Mark Flekken said that he has “finally adapted to the league and found my place” following Brentford’s 3-1 defeat to Man City.
The Dutchman was in fine form on Monday night, making 12 saves – the joint-most in a Premier League match since 2 December 2017 (David De Gea, 14 saves v Arsenal).
“You just keep going to the next one; you don’t start counting during the game,” he said.
“It feels like I’ve finally adapted to the league and found my place. I’ve got back to the level I used to be before my transfer to Brentford. It finally fits together, all of the pieces, and that feels good.
“It feels good to finally be able to show what kind of keeper I can be.”