Caoimhín Kelleher continued his penalty-saving exploits to deny Bruno Fernandes as Brentford piled the pressure on Manchester United at the Gtech Community Stadium with a 3-1 victory.
The former Liverpool shotstopper earned a reputation on Merseyside with impressive displays in penalty shootouts, and had also saved three of the previous five Premier League penalties he had faced.
Igor Thiago's first-half double put Brentford in command before United were handed a lifeline by Benjamin Sesko’s first goal since his £73million move from RB Leipzig.
Fernandes was looking to equalise from the spot in the 74th minute after Bryan Mbuemo, back at Brentford after ending a six-year stay with the Bees in the summer, was fouled Irish defender and Bees captain Nathan Collins.
But Fernandes, who missed the target from 12 yards at Fulham last month, was wasteful as the Corkman went to his left and saved with a strong hand.
Substitute Mathias Jensen sealed matters in the fifth of eight minutes of stoppage time.
Brentford had won only once in the Premier League and started the day just outside the bottom three, but an excellent team performances was typified by the excellent Jordan Henderson and Mikkel Damsgaard in midfield and Igor Thiago’s clinical finishing.
Diogo Dalot, Manuel Ugarte and Matheus Cunha returned after United’s win over Chelsea with boss Ruben Amorim’s hand forced by injury and suspension.
Noussair Mazraoui was injured, Casemiro ruled out by his Chelsea red card, and Amad Diallo unavailable due to a family bereavement.
It meant summer signings Cunha, Mbeumo – who received a warm reception on his Brentford return – and Sesko lined up in the United attack for the first time .
Brentford profited from the first main action after eight minutes as Cunha went to ground and Henderson spotted Thiago’s run.
Thiago advanced to crash a shot high off the post past Altay Bayindir, and the subsequent VAR check showed the Brazilian had been played onside by Harry Maguire’s back foot.
Cunha drove wide from 20 yards as United sought to recover from the early setback.
But Bayindir had to make two fine stops in the space of a minute, palming out Sepp van den Berg’s point-blank effort and acrobatically tipping over a Collins header after Henderson had found space.
Brentford were swarming all over United and doubled their lead after 20 minutes.
Maguire played Kevin Schade onside this time and Bayindir could only divert his cross into the path of Thiago, who squeezed the ball over the line despite the desperate effort of the United goalkeeper to salvage the situation.
Sesko fired straight at Kelleher, but the Slovenian striker did not have to wait long to open his United account.
Mbeumo competed with Kelleher under Patrick Dorgu’s cross and the ball fell kindly for Sesko.
Kelleher kept out two attempts – a header and a stabbed shot – but Sesko slammed home at the third attempt and the goal stood after VAR had checked Mbeumo’s challenge on the goalkeeper.
Cunha’s low drive was collected comfortably, but the second half was a more sedate affair until Schade got the better of Dalot and Dango Ouattara was denied by Bayindir.
United’s frustration grew after Collins was spared a red card, despite not appearing to try and play the ball when holding back Mbeumo, and Fernandes missed from the spot.
Jensen’s thunderous drive finally saw off United as jubilant Brentford fans directed cries of "you’re getting sacked in the morning" at Amorim.
