Yossi Benayoun took advantage of a defensive lapse to help West Ham earn a battling draw at Sunderland.
Sunderland's Andy Gray saw an early free header saved before Tommy Miller's close-range finish just before the break gave the home side the lead.
West Ham were on the back foot after the interval and were thankful for several saves from keeper Roy Carroll.
But Benayoun raced through after the ball rebounded off a defender and finished smartly past Kelvin Davis.
Sunderland suffered a blow before kick-off when Julio Arca - so impressive when the Black Cats earned their first Premiership win in 27 attempts at Middlesbrough last weekend - was ruled out through injury.
But despite the Argentine's absence, both sides signalled their attacking intent from the outset - and each squandered one golden chance in the opening 10 minutes.
Sunderland should have taken the lead on four minutes, but Andy Gray headed straight at Roy Carroll after losing his marker Anton Ferdinand.
And five minutes later, West Ham striker Marlon Harewood pounced on a loose ball inside the area and forced a smart parry from Sunderland keeper Davis.
But the excitement quickly petered out, although the Hammers were thankful that Danny Gabbidon got his head to Andy Welsh's cross with Stephen Elliott lurking just behind him.
Sunderland suffered a blow when Christian Bassila was forced off the field 10 minutes before half-time with what appeared to be a hamstring injury, Liam Lawrence coming on as a replacement.
And Lawrence was instrumental in Sunderland's opener in first-half injury time.
Justin Hoyte fed Lawrence whose low cross was stopped by Carroll's foot - only for the ball to bounce straight to Miller, who fired high into the net from close range for his second goal in two matches.
Sunderland began the second period buoyed by the goal, and Elliott saw one promising break end when Carroll plucked his looping cross out of the air at full stretch - and was penalised, perhaps harshly, as Sunderland had a goal disallowed.
Yet it was the Hammers who fashioned the first clear opening after the interval, Tomas Repka's superb long pass picking out Teddy Sheringham who sliced his lob well wide of the goal with Davis beaten.
Sunderland still looked the more threatening side, however, and Elliott fired a shot which Carroll blocked with his feet - then saw Dean Whitehead's goal-bound shot hit team-mate Gray.
Lawrence also forced Carroll into action with a long-range drive and Sunderland seemed to be cruising.
Yet a defensive mix up gave Benayoun the chance to level and the Israeli did not disappoint.
The ball rebounded kindly off a Sunderland defender and Benayoun latched on to race clear and finish smartly past Davis.
The goal stunned the home fans and although Elliott saw a late deflected shot saved by Carroll it was West Ham who finished stronger.
Sunderland boss Mick McCarthy:
"We've played very well, we dominated the game in the second half. I know if we go anywhere away and get dominated like that we'll lose.
"But lets take the positives out of it, we are unbeaten in four games. It is another point for us.
"We've got to finish above three teams and that's another point to our tally."
West Ham boss Alan Pardew:
"You have to take your hat off to the opposition sometimes. We did not a get a chance to play out, when we did they were swarming all over us.
"Their organisation was spot on, they did a job. The good news for us is that we've had someone biting us on the bottom and we have reacted to it.
"We've showed a bit of quality and the goal knocked energy out of them."
Sunderland: Davis, Nosworthy, Breen, Caldwell, Hoyte, Whitehead, Bassila (Lawrence 36), Miller, Welsh (Daryl Murphy 87), Gray, Elliott.
Subs Not Used: Collins, Le Tallec, Joe Murphy.
Goals: Miller 45.
West Ham: Carroll, Repka (Dailly 68), Ferdinand, Gabbidon, Konchesky, Benayoun, Reo-Coker, Mullins, Etherington (Newton 68), Sheringham (Zamora 62), Harewood.
Subs Not Used: Hislop, Bellion.
Booked: Gabbidon, Konchesky, Newton, Benayoun, Reo-Coker.
Goals: Benayoun 72.
Ref: M Atkinson (W Yorkshire).