For the second time in ten days, Alan Pardew made a miserable return to one of his former clubs as ten-man Hammers slumped to their fourth successive away defeat, at Selhurst Park.
Dougie Freedman's 66th-minute winner settled an ill-tempered London derby that saw workmanlike West Ham free-fall out of the coveted Play-off berths and into eighth place, as Palace moved to within just one point of the East enders.
"We didn't lose that game through any lack of effort," argued the Upton Park boss after seeing the twice-booked David Connolly dismissed ten minutes before the interval. "You certainly couldn't question our work-rate and there was a lot of care out there. We showed we were up for it today and we saw some good performances but the sending off proved to be the turning point.
"It was a harsh decision in the circumstances because I hoped that the referee might have shown a bit more understanding in a tense derby. If he had been a bit firmer earlier on, it would not have developed into such a fraught game but, then again, we all have our off days.
"Our fans stayed with us, though, and my ten men fought for every ball and that shows that the fire is still there for everyone here at the club."
Pardew had made four changes from the side that had been held at home by Derby County as he effectively replaced Saturday's entire starting midfield, bringing back Nigel Reo-Coker, Jobi McAnuff, Kevin Horlock and right-back Anton Ferdinand.
That saw Michael Carrick (groin), Steve Lomas (rested), Chris Cohen and Bobby Zamora step down while the industrious Hayden Mullins moved into midfield to face his old club and a fired-up Marlon Harewood headed forwards into a richly-sought striking role alongside Connolly.
With the Play-offs still in their sights, Palace come into the match boasting back-to-back victories over Rotherham United and Cardiff City and ex-Hammer Iain Dowie made just one change as Freedman replaced Neil Shipperley in attack.
Certainly, both sides wasted no time showing that they were desperate for the win that would keep their promotion push on track, and Referee Bates proved the busiest man on the pitch in a disjointed game that quickly saw him book Aussie Tony Popovic for a crude, early chop on McAnuff.
And on 13 minutes, Tomas Repka then collected an all too familiar 16th yellow card of the campaign for a late, late lunge on the fleeing Andy Johnson that had the Selhurst Park regulars baying for red.
As both sides struggled to settle into their stride in a first-half punctuated by 23 free-kicks, Jon Harley and Reo-Coker sent long-rangers over the top, before Connolly became the third name to go into the book on the half-hour mark for a forceful check on Danny Granville.
Indeed, it was to get even worse for Connolly just six minutes later when he charged into Danny Butterfield on the right-hand edge of the Palace area and was promptly dismissed for a second bookable offence that left Hammers vehemently protesting their team-mate's innocence.
How West Ham's 7,600 fans must have been wishing that the Irish international striker was still on the field in first-half stoppage time.
For when the visitors breached Palace's poorly conceived offside trap, Repka's well-flighted free-kick fell to central defender Christian Dailly who rashly volleyed over from 12 yards with just the exposed Nico Vaesen to beat.
Harewood also found time to scuff wide before Butterfield finally mustered the game's first shot on target with a blistering 20-yarder that Pavel Srnicek clutched at the second time of asking, and as an ill-tempered first period drew to a close there were yet more heated exchanges when both sides headed for the tunnel.
Predictably, Hammers soon found themselves under pressure after the break, too, as Palace looked to press home their extra-man advantage, but marshalled by skipper Dailly, Ferdinand, Repka and Harley threw themselves at everything that came their way.
Midway through the half, however, the escaping Julian Gray managed to unleash a stinging, angled ten-yarder which Srnicek brilliantly beat aside.
But sadly that was to prove brief respite, for when substitute Shaun Derry floated over the subsequent corner, Johnson nudged the ball into the six-yard box where Freedman bundled his 13th goal of the season over the line.
Both Zamora and Cohen were introduced in quick succession as McAnuff and Harley retired, but it was Palace who came closest to doubling their lead as Srnicek twice foiled the breaking Johnson with his outstretched legs inside the space of 60 seconds.
Substitute Brian Deane was introduced on 78 minutes but still 'keeper Vaesen remained untroubled and without a shot on target to save, while Referee Bates finished off a busy afternoon by booking Cohen and Zamora for late fouls on Gray and Mark Hudson.
"We've still got a great chance of making the Play-offs and a home victory against Coventry City next week will put us back on track," insisted Pardew who hopes that Carrick, Matthew Etherington and Steve Lomas will be available for what is now a must-win game if Hammers are to regain a must-have top six spot with just four fixtures remaining.