West Ham are hot on the heels of Championship leaders Southampton after Papa Bouba Diop secured a 1-0 win over Barnsley at Upton Park on Saturday.
With Southampton not in action until Sunday's south-coast derby at bitter rivals Portsmouth, Sam Allardyce's Hammers had a golden opportunity to move level on points with Saints at the top of English football's second tier.
They took the chance thanks to Senegal midfielder Diop, who scored in the sixth minute to claim his first goal in English football since netting for Fulham against Blackburn six years ago.
West Ham, who ended a run of two successive defeats, remain in second place but only goal difference is keeping them below Southampton.
Middlesbrough moved above Cardiff into third place after a dramatic 3-2 win at their promotion rivals.
Bart Ogbeche beat David Marshall with a deflected effort to hand the visitors the advantage against the run of play, but Boro's ascendancy was short-lived.
Ben Turner nodded his first goal for Cardiff to restore parity before Aron Gunnarsson latched onto Kenny Miller's neat pass to slot home the hosts' second of the afternoon.
Boro drew level when Justin Hoyte picked out Scott McDonald, who tapped home before Faris Haroun struck the winner with 15 minutes remaining to end Cardiff's 11-game unbeaten run.
Hull also moved above Cardiff into third with a 2-0 win over struggling Millwall at the KC Stadium.
Caretaker boss Nick Barmby underlined his claims to get the Hull job on a permanent basis as the Tigers took the lead in the 54th minute through Jack Smith's own goal and a Robert Koren effort in the 80th minute sealed the points.
Leeds remain sixth despite losing 1-0 at home to Reading, who boosted their own play-off push thanks to a cool lob from Simon Church in the second minute.
Kieran Trippier scored the only goal as Burnley won 1-0 away to nine-man Brighton.
The on-loan Manchester City defender netted following a short corner on the half hour but referee Craig Pawson will be seen as the villain by home fans after sending off both Romain Vincelot and Ashley Barnes inside the opening 12 minutes.
Billy Sharp netted twice in two second-half minutes as Doncaster came from behind to win 2-1 at home to Leicester, while Keith Andrews got the only goal as Ipswich won 1-0 against Derby.
Emile Sinclair netted for Peterborough as they won 1-0 against bottom club Coventry at London Road.
Blackpool and Watford shared a 0-0 draw and Bristol City and Nottingham Forest also played out a goalless draw.