Leeds' automatic promotion hopes suffered a major setback as they slumped to a shock 2-1 defeat at home to 10-man Wigan.
Sheffield United had moved ahead of Leeds into second place on goal difference earlier in the day after beating Nottingham Forest 2-0 and Marcelo Bielsa's men were unable to respond, despite playing with an extra man following the 14th-minute dismissal of Cedric Kipre and going ahead through Patrick Bamford three minutes later.
Kipre was sent off for a handball on the line and, although Pablo Hernandez hit a post with the resulting penalty, Bamford's crisp finish soon broke the deadlock at Elland Road.
However, Wigan responded with a superb counter-attack from a Leeds corner to set up Gavin Massey to equalise and the same player headed what proved to be the winner in the 62nd minute as the visitors' survival hopes received a huge boost.
Second-half goals from Mark Duffy and Enda Stevens gave the Blades victory over 10-man Forest, who had Yohan Benalouane sent off two minutes into the second half for bringing down David McGoldrick on the edge of the area.
Leaders Norwich are five points clear but could only draw 2-2 at home to Sheffield Wednesday last night.
At the other end of the table, Bolton's relegation was confirmed as they went down 2-0 at home to in-form Aston Villa.
Former Watford owner Laurence Bassini agreed a deal to buy Bolton earlier this week, subject to approval from the English Football League.
But Wanderers will be playing League One football next season after second-half goals from Jack Grealish and Tammy Abraham sealed their fate.
Middlesbrough moved above Bristol City into the play-off places thanks to 1-0 win over Stoke, Britt Assombalonga scoring the only goal after three minutes.
City had earlier needed a 72nd-minute equaliser to earn a point at home to Reading, who took the lead three minutes into the second half when Yakou Meite converted a slick free-kick routine.
West Brom remain fourth after edging a five-goal thriller with Hull. Kieran Gibbs volleyed home the opener shortly before the interval before Todd Kane levelled for the visitors just three minutes into the second half with a thumping drive.
Kane produced another superb finish to fire Hull in front after 59 minutes, only for Dwight Gayle to level with a stooping header from close range and then grab the winner five minutes from time.
Third-bottom Rotherham's survival chances suffered a major blow as they lost 4-3 at Swansea.
Birmingham and Derby played out an entertaining 2-2 draw at St Andrew's.