Winston Reid's last-minute goal snatched a dramatic 1-0 victory for West Ham over Sunderland at the London Stadium on Saturday.
It looked as though the Hammers were set for another frustrating result at their new home, with Dimitri Payet going closest to breaking the deadlock when he hit the post in the 27th minute.
Wahbi Khazri missed a brilliant chance for Sunderland early in the second half, and the visitors were denied a point with almost the last kick of the match as Reid fired in from the edge of the box.
The goal stood despite a question of offside and West Ham have now secured back-to-back wins for the first time this season while Sunderland remain rooted to the foot of the Premier League table with just two points to their name.
Even at such an early stage of the season the Black Cats look in deep trouble, although David Moyes will be aggrieved not to have taken a point from their visit to the capital.
The hosts, who had only won once previously in the league at the London Stadium this season, made an enforced change with the suspended Aaron Cresswell replaced by Edimilson Fernandes.
Lamine Kone and Steven Pienaar started for Sunderland, who were distinctly second best in the early stages. Payet curled an effort narrowly wide and shot at Jordan Pickford after dribbling his way into the box.
West Ham also had a couple of penalty appeals waved away before Payet went even closer in the 27th minute as he opened up space with a clever dummy and then shot against the post from just inside the box.
After weathering the storm, Sunderland eventually grew into the game and Jack Rodwell headed over from Khazri's free-kick.
Patrick van Aanholt shot over from 20 yards before the otherwise ineffective Simone Zaza saw an overhead kick fly just wide of the post.
Khazri spurned Sunderland's chance of the match early in the second half when he was played through on goal and failed to beat Adrian.
A similar opportunity presented itself to Zaza moments later but his poor first touch allowed Kone to recover.
Otherwise, West Ham largely looked laboured and aside from Fernandes shooting over from the edge of the box they struggled to break down Sunderland's compact defence.
It looked as though they would have to make do with a share of the spoils until the final minute when a corner was played to Reid just outside the area and his low shot went through a crowd of bodies - with a West Ham player seemingly in an offside position - and into the net.
Player ratings
Sunderland: Pickford (6), Manquillo (6), Kone (7), O'Shea (7), Van Aanholt (6), Watmore (6), Rodwell (6), Ndong (6), Pienaar (5), Khazri (5), Defoe (6).
Subs: Jones (5), McNair (5), Gooch (5).
West Ham: Adrian (6), Reid (8), Kouyate (6), Ogbonna (6), Antonio (5), Noble (7), Obiang (7), Fernandes (7), Lanzini (6), Zaza (5), Payet (6).
Subs: Feghouli (5), Fletcher (5), Calleri (5).
Man of the match: Winston Reid.