Martin Jol's chances of hanging on to his job took a serious blow as West Ham condemned struggling Fulham to their fifth straight league defeat by winning 3-0.
Mohamed Diame's deflected shot beat Maarten Stekelenburg and substitute Carlton Cole scored his first goal of the season before Joe Cole sealed the win for the Hammers.
Jol admitted prior to the match that he could lose his job if his team were defeated, and Fulham fans made their feelings clear in the second half, chanting "Jol out!" and "You're getting sacked in the morning!"
The Dutchman remained on the bench for most of the game, with his new right-hand man Rene Meulensteen barking orders at the team.
Speculation will surely increase that the former Manchester United coach will replace his compatriot following the team's ninth defeat of the season.
Some Fulham fans chanted Meulensteen's name towards the end. They clearly want him to replace Jol as soon as possible.
One thing is for sure - Fulham need to improve fast. Only Adel Taarabt came away from this match with any credit. Without the ill Dimitar Berbatov, the Cottagers lacked any conviction up front and Fulham cannot afford to commit sloppy errors like the one that Sidwell made in the build-up to the first goal.
Fulham remain in the relegation zone, but for West Ham, the win - their first at home since the opening day of the season - was a welcome boost.
Manager Sam Allardyce dispensed with the "false nine" system and it paid off as the Hammers put on a clinical display of attacking football.
West Ham were booed off following last week's defeat to Chelsea, so captain, chairman and manager united in their programme notes to urge the fans to get behind their team.
The home side started well. Matt Jarvis and Stewart Downing stretched the Fulham defence with some incisive runs and Modibo Maiga looked lively.
West Ham peppered the Fulham box and Mark Noble may have given the hosts the lead had his shot not been blocked by former team-mate Scott Parker, who captained Fulham in the absence of Berbatov.
Maiga stole in front of his marker to meet Noble's free-kick but his effort struck a post and bounced out to safety.
Sensing the importance of the game, both teams were really going for it. Tensions boiled over on two occasions, resulting in bookings for Kieran Richardson and James Tomkins, who cleaned out Pajtim Kasami with a late two-footed challenge. Sidwell would later join them for a similar foul on Diame.
Other than the odd run from Taarabt, Fulham looked impotent in attack. Elsad Zverotic piled a long-range free-kick into the Bobby Moore stand.
James Collins was the next man to go close for West Ham when he headed a Downing cross inches wide. Downing had a go himself moments later, but Maarten Stekelenburg saved.
West Ham were fortunate to keep George McCartney on the pitch just before the break when the left-back tugged at Darren Bent's shirt, sending the former Aston Villa man tumbling to the ground just outside the box.
Luckily for the Hammers, Martin Atkinson saw it as a booking only.
Still, Fulham had a good opportunity to test Jussi Jaaskelainen, but the fans were once again sent scrambling for cover as Richardson thumped the set-piece way over the bar.
Nolan horribly messed up an overhead kick, but West Ham were clapped off the pitch at half-time for their efforts.
Those fans had to wait just 72 seconds after the restart before they saw their team go ahead. Fulham helped them on their way. Parker lost possession 30 yards out and Sidwell then dallied on the ball, allowing Diame to advance towards goal. The midfielder fired a low drive which flicked Amorebieta's leg, diverting the ball past a helpless Stekelenburg.
West Ham pushed for a second. Stekelenburg saved well from Maiga and Downing fired the follow-up just over the bar.
Bent cleared Tomkins' header off the line. Jol brought on Bryan Ruiz, but West Ham continued to dominate.
Stekelenburg saved a close-range header from Jarvis and Downing then curled an effort on to the bar.
Kasami fired a warning with a low shot that skidded just wide of Jaaskelainen's goal.
Fulham's travelling support had seen enough. With 15 minutes left they knew their team were not capable of equalising and they sang "Jol out!" en masse.
Allardyce strengthened his team by bringing on Joe Cole, Carlton Cole and Ravel Morrison.
The latter crashed a shot barely an inch wide but Carlton Cole did not miss his opportunity, tapping in Downing's cross.
Allardyce and his coaching staff sprung from the bench in glee. Jol just sat there, looking despondent.
The Dutchman then had his head buried in his hands two minutes from time when Joe Cole wrapped up the win for the hosts.