Second placed West Ham won their fourth successive match after goals from Frederic Piquionne and Carlton Cole earned them a win over Middlesbrough.
Piquionne headed in Matt Taylor's early cross although Hammers goalkeeper Robert Green had to be sharp to deny Scott McDonald an instant equaliser.
Tony Mowbray's Middlesbrough had not lost at home for 16 matches, but could not find a way past Green.
Cole rounded goalkeeper Jason Steele to seal the win in injury time.
Marvin Emnes looked the most likely home player to force a breakthrough, but he and McDonald were denied by Green as the first half drew to a close.
Mowbray's side increased their work-rate in the second period, and Faris Haroun shot wide after Joe Bennett played a dangerous ball into the penalty box.
West Ham could have increased their lead on the hour mark when Papa Bouba Diop was presented with a clear opportunity but shot wide instead of passing to Kevin Nolan - the former Bolton man would have loved to have marked his 400th career game with a goal.
Despite bringing on Bart Ogbeche, Julio Arca and Alex Nimely from the bench, Boro were to lose their unbeaten home record, and Cole secured all three points when he benefited from a poor Boro clearance.
The England striker rounded Steele and finished calmly despite the presence of two Boro defenders on the goal-line - sending the 1,243 travelling fans in to raptures as they celebrated their fourth straight win away from home.
After Middlesbrough's defeat, only Southampton and Birmingham now have unbeaten home records in the Championship this season.
West Ham manager Sam Allardyce said after the game: "We got every element right today. When we had to defend, we defended well, when we attacked, we exploited the spaces they were leaving to show our quality in the final third.
"We're a very happy bunch at the minute, we're just keeping our feet on the ground, enjoying our training and enjoying our time together. We prepared right for this one today."
Middlesbrough boss Mowbray was frustrated with his side's performance, saying: "It was one of those nights we huffed and puffed and had a few chances but I never really sat on the edge of my seat.
"They've got a lot of Premier League experience and I think it showed. We'll take it on the chin and move on."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.