Nacer Chadli netted a brace and provided two assists on his home debut as West Brom survived a second-half onslaught to claim a dramatic 4-2 Premier League victory over West Ham at The Hawthorns.
Slaven Bilic's side looked well beaten when Chadli - who had given West Brom the lead with an eighth-minute penalty before additional first-half strikes from Salomon Rondon and James McClean - made it 4-0 to Tony Pulis' men just after the hour mark.
However, West Ham came on strong in a thrilling final quarter of the match, Dimitri Payet rattling the woodwork before supplying a brilliant cross that top-scorer Michail Antonio headed home.
West Brom, who had never scored four in a Premier League encounter under Pulis before Saturday's clash, failed to cope as West Ham upped the pressure following Antonio's effort, Manuel Lanzini converting from the spot after Payet was scythed down in the area.
But despite a late surge, West Ham, who have now taken just three points from a possible 15, could not find the target again as they slumped to a second successive 4-2 defeat.
Boosted by the completion of a takeover by Chinese investment group Yunyi Guokai Sports Development Limited this week, West Brom were rewarded for a bright start when Arthur Masuaku inexplicably handled in West Ham's area seven minutes in.
Chadli, making his second appearance since arriving from Tottenham, stepped up to convert the resulting spot-kick, drilling a well-placed finish into the bottom-left corner, sending Adrian the wrong way.
West Ham should have been further behind moments later, but Rondon could only hammer his close-range strike straight at Adrian.
Bilic's side finally managed to create a clear-cut chance after 35 minutes, Ben Foster rushing out to make a point-blank save to deny Antonio.
And the visitors were made to pay for that miss two minutes later as West Brom doubled their lead - Chadli capitalising on Angelo Ogbonna's poor clearance before teeing up Rondon, who proceeded to thump a precise effort past Adrian.
West Ham were a shambles at the back and West Brom duly had their third on the stroke of half-time, Chadli again involved as his low shot from the edge of the box was turned home by McClean.
It was 4-0 shortly after the restart, West Ham's defence again exposed as Rondon raced clear before slipping a neat pass into the path of Chadli, who had the simple task of tapping in his second.
The visitors refused to give in, though and, after Payet had struck the corner of the upright and crossbar with a fabulous free-kick, they pulled one back through Antonio's fifth of the season.
Antonio's header sparked West Ham into life, Payet surging into the area and drawing a foul from Brendan Galloway - Lanzini making no mistake with his penalty.
West Ham dominated proceedings as the game approached a frantic conclusion, Payet going close with a dipping effort before Foster made a superb save to deny James Collins.
But West Brom held firm to secure the spoils - a timely win for Pulis following recent reports casting doubt over his future at the club.
Key Opta stats:
- Nacer Chadli's penalty was the eighth that Albion have been awarded in the Premier League since December 2014, but only the third that they have converted.
- This was the first penalty that Chadli has taken in the Premier League, despite it being his 90th appearance in the competition.
- Rondon has now scored in four of his last seven Premier League appearances for West Brom (four goals).
- Antonio has scored more headed goals on his own (5) than any other team in the Premier League this season.
- The Hammers have conceded at least two goals in 12 of their last 15 Premier League matches (33 goals conceded overall).