West Ham 1 Bolton 3
England keeper Robert Green's blunder helped Bolton on their way to a 3-1 win over high-flying West Ham at Upton Park which ended Gianfranco Zola's 100% Premier league record.
The normally reliable Hammers number one lost his grip in the wet conditions on the half-hour mark as he dropped the ball at the feet of Kevin Davies, who hooked it into an empty net.
Green then failed push a low shot wide enough, with Gary Cahill bundling in from close range.
The Hammers, who could have gone top of the table with a victory, got a lifeline through Carlton Cole on the hour, but substitute Matt Taylor made sure of an away win with a 30-yard free-kick four minutes from time.
The weather had cleared somewhat by kick-off - but the pitch remained sodden after the torrential downpours which had fallen over east London all morning.
The ball was moving fast on the slick surface, and West Ham were happy enough to work some quick passes.
The visitors, who started proceedings out of the relegation zone only on goal difference, sent in couple of high balls into the penalty area to test Green, in a sign of things to come.
The first decent opening came after 12 minutes.
Cole, the Hammers main attacking threat following injury to England striker Dean Ashton, collected the ball 25 yards out and made space for a shot, which flew just over the crossbar.
Bolton broke quickly and had a sight of goal themselves when Sweden forward Johan Elmander was slipped through, but his effort lacked any power to trouble Green.
West Ham threatened again when on-loan full-back Herita Ilunga burst into the left side of the penalty area and towards the goal-line before his low, angled effort was blocked by Jlloyd Samuel.
In the 29th minute, Valon Behrami tried his luck from 20 yards with a low strike which skidded off the wet surface and just wide of the left-hand post.
However, it was Bolton who took the lead on the half-hour following a bad error by Green.
The keeper came to the edge of his area to make what should have been a routine collection from a high ball.
However, the England squad man fumbled and promptly dropped the ball right at the feet of Davies, who hooked it into an empty net.
Before the Hammers had time to regroup, they were further behind.
A free-kick into the penalty area was headed out, but only as far as Gretar Rafn Steinsson, who sent in a fierce low strike.
Green got down quickly to make a decent reaction save - but the ball broke lose and Cahill was on hand to prod it over the line for his first Bolton goal since a £5m move from Aston Villa in January.
The home side were now well and truly shell-shocked, with Bolton pressing forwards at every opportunity.
Half-time could not come quick enough for Zola, who has his work cut out to avoid a first league defeat since taking over from Alan Curbishley last month.
West Ham looked to find an early way back into the match following the restart, but despite continued possession, the home side again lacked ideas in the final third.
However, only a stunning save from Jussi Jaaskelainen prevented them from pulling a goal back on 50 minutes.
Cole made space for himself to turn some 25 yards out and sent in a looping shot which flew over the Bolton keeper - but he somehow got his trailing hand to the ball and pushed it onto the post.
After Wales striker Craig Bellamy was sent on, the home side upped the pace, but too often gave away possession.
Gavin McCann almost wrapped things up for Bolton with a side-foot effort from 25 yards which skidded just wide.
Jaaskelainen spilled a long-range shot from Scott Parker, but there were no West Ham players following up - much to the despair of the Upton Park faithful behind the goal.
The Hammers then had a lifeline on 68 minutes.
Matthew Etherington's corner from the right was nodded back into the six-yard box where Cole arrived to head the ball in off the underside of the crossbar and chalk up a fourth goal of the season.
West Ham, buoyed by the home fans who had suddenly found their voice, pressed again as Behrami fired wide.
There was certainly more urgency about the Hammers now, if still lacking an end product.
However, Bolton sealed a first away victory of the campaign when substitute Taylor smashed in a 30-yard free-kick four minutes from time.