West Ham narrowed the gap to Southampton at the top of the Championship to two points as they came from behind to win 3-1 against Derby.
Tamas Priskin fired in his first goal for the Rams, only two days after arriving on loan from Ipswich, after Jamie Ward's run and pass.
Carlton Cole's header levelled the scores shortly before half-time and Kevin Nolan's volley made it 2-1.
Mark Noble added a third from the penalty spot later in the second half.
The result means Sam Allardyce's side have extended their unbeaten run to six games, while Derby suffered their fourth successive defeat.
West Ham's evening started badly when Sam Baldock had to come off with a hamstring injury.
Shortly afterwards, Jack Collison nearly caught goalkeeper Frank Fielding out with a shot on the turn, but the visitors' keeper held the ball at the second attempt.
That, after 28 minutes, was West Ham's first shot on target and Derby responded by scoring with the game's next chance six minutes later.
Collison was caught in possession on the halfway line and that presented Ward with the chance to cut in from the left flank and find Priskin. James Tomkins remained static, losing the Hungary international, and he fired the ball into the far corner.
West Ham were back on level terms one minute before half-time thanks to Cole.
The visitors had cleared Abdoulaye Faye's free-kick but Joey O'Brien sent a first-time cross back in, which Cole directed past John Brayford, who was covering on the line.
Baldock's replacement Frederic Piquionne nearly put the hosts ahead early in the second half. Julien Faubert lofted a ball over the defence and the French striker brought the ball down expertly but his shot was blocked by Fielding.
Allardyce's side continued to press and they got their reward when Nolan fired them into the lead with a sublime show of technique 19 minutes after the break.
Collison diverted the ball in the midfielder's direction and he waited patiently for it to drop before planting a volley into the bottom corner of the net from 25 yards out.
The hosts then wrapped up the points 10 minutes later through Noble's spot-kick, slammed into the top corner, after Craig Bryson had pushed Piquionne in the box.
It could have been worse for Derby had full-back Gareth Roberts not cleared Piquionne's glancing header off the line near the end.
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.