Watford claimed their first away victory of the season with a deserved win over relegation rivals West Ham.
Henderson beats West Ham's Green with his first goal of the season
Darius Henderson put Watford ahead when he was pulled back by Anton Ferdinand in the box and scored from the spot.
Bobby Zamora's poor finishing saw West Ham waste chances, while Ben Foster did well to save Yossi Benayoun's drive.
Marlon Harewood made things worse when he missed a penalty after Gavin Mahon fouled Nigel Reo-Coker - and rock- bottom Watford held on to the points.
Adrian Boothroyd had urged his Watford side to show more fight and less fear before the match and his words seemed to have had an effect.
The Hornets strung together some early attacks with Jordan Stewart, Steve Kabba and debutant Johan Cavalli working well through midfield.
West Ham's frustration soon told when Ferdinand grappled Henderson by the shoulder and conceded the penalty after 13 minutes.
After a delay, during which Calum Davenport went in the book for his blatant encroachment, Henderson slotted the ball into the far left corner, scoring Watford's first penalty of the season.
West Ham looked for an immediate reply; Matthew Etherington testing new England keeper Ben Foster with a swinging free-kick and Davenport coming close with a header.
Zamora had the best chances to equalise but twice failed to find the target from good positions, instead skimming the ball over the bar.
In fact, Zamora was so desperate to score he even nicked the ball from Foster when the keeper dropped it and the pair engaged in a comedic scramble until the referee awarded Foster a free-kick.
Foster showed his calibre before the break, leaping sideways through the air to push clear Benayoun's drilled effort with a brilliant save.
For all their efforts, West Ham could not find a way past Watford's rigid defence and Alan Curbishley's men were rewarded with ringing boos at half-time.
Carlos Tevez came out in place of Zamora and immediately made his presence felt, as his curling free-kick just inched wide of the post.
The Argentine came within a whisker of his first goal for the club when he wriggled past Foster and thumped the ball goalbound - only for Malky Mackay to stick his foot out and make a last-ditch deflection.
West Ham's misery continued when Harewood lamely wasted yet another chance to equalise.
The striker stepped up to take the Hammers' first penalty of the season after Reo-Coker was brought down by Mahon but, after a short run-up, he scuffed his shot wide. Curbishley shook his head on the sidelines.
Urged on by an anxious Upton Park crowd, West Ham kept their heads and pressed forward.
Tevez lashed another stinging shot just wide from the right but apart from that flashpoint, the Hammers were efficiently closed down by Watford.
Watford's win saw them move to within two points of 19th-placed Charlton, while Curbishley ponders a return to his former club for another relegation tussle next.
West Ham boss Alan Curbishley:
"We gave away a soft penalty and I think Anton will look back and wonder what he was doing.
"If we had scored our penalty it would have been a different story but we've not had much luck since I've been here.
"This has been a devastating blow for us but we have to pick ourselves up and Charlton is a must-win game now."
Watford manager Adrian Boothroyd:
"I wanted to play it down but I'm going to savour this win because we've not had much to shout about
"We want to build on this momentum and take it into the next game. Everyone thinks we are down anyway so we're playing with nothing to lose.
"We looked relaxed today, the whole team is buzzing and it is going to be exciting right until the death."
West Ham: Green, Neill (Spector 32), Ferdinand, Davenport, McCartney, Benayoun, Reo-Coker, Quashie (Boa Morte 80), Etherington, Harewood, Zamora (Tevez 46).
Subs Not Used: Carroll, Dailly.
Booked: Davenport, Spector, Benayoun, Reo-Coker.
Watford: Foster, Mariappa, DeMerit, Mackay, Stewart, Smith, Mahon, Francis, Cavalli (Bangura 75), Henderson (Shittu 90), Kabba (Ashikodi 79). Subs Not Used: Priskin, Hoskins.
Booked: Mariappa, Ashikodi.
Goals: Henderson 12 pen.
Ref: A Wiley (Staffordshire).