Substitute Charlie Austin netted a decisive stoppage-time penalty as Southampton weathered a valiant fightback by 10-man West Ham United on Saturday to record a 3-2 victory.
Southampton ended a club-record run of six home games without scoring to go 2-0 up through Manolo Gabbiadini and Dusan Tadic, with West Ham's Marko Arnautovic sent off in between for elbowing Jack Stephens.
Former Manchester United striker Javier 'Chicharito' Hernandez scored his first two West Ham goals to draw the visitors level, only for Austin to snatch victory at the death.
Austin's 93rd-minute effort, after a foul on Maya Yoshida by Pablo Zabaleta, prevented Mauricio Pellegrino's side from going seven home league games without victory.
It was another punch in the guts for West Ham manager Slaven Bilic, albeit of a different kind to last weekend's 4-0 thrashing at Manchester United.
The east London club have lost their opening two league games for the first time since 2010-11, when they were relegated.
Their afternoon took a turn for the worse before the game had even kicked off as Winston Reid injured his calf in the warm-up and had to be replaced by Angelo Ogbonna.
Southampton awarded a debut to record signing Mario Lemina, who was bought from Juventus for a reported initial fee of £15.4 million ($19.8 million, 16.9 million euros).
The hosts ended a goal drought of 586 minutes in the 11th minute, Gabbiadini exchanging passes with Nathan Redmond before beating Joe Hart for his first goal in 10 games.
West Ham threatened to come back into the game and it took a superb reflex stop from Fraser Forster to prevent Hernandez equalising with a diving header from an Arnautovic cross.
But after Mark Noble had avoided punishment for an ugly challenge on Lemina, West Ham shot themselves in the foot when Arnautovic saw red for flinging his arm into Stephens's neck.
Within five minutes it was 2-0 as Tadic netted from the penalty spot after Southampton old boy Jose Fonte had been penalised for hauling down Steven Davis.
West Ham gave themselves a lifeline on the stroke of half-time when Hernandez scored after Forster had parried a shot from the fit-again Michail Antonio.
After Gabbiadini had clipped the bar, Hernandez equalised in trademark fashion in the 73rd minute, volleying in after Diafra Sakho's effort came back off the bar.
But Austin had the last word, tucking a nerveless penalty past Hart after Zabaleta was penalised for a push on Yoshida.