West Brom went top of the Championship on Wednesday, while Wigan Athletic and Middlesbrough gained key wins at the other end of the table.
The Baggies moved above Leeds United, and went five points clear of third-placed Brentford, with a 2-0 victory over Derby County, who saw their play-off hopes dented by the loss.
Grady Diangana and Dara O'Shea scored in either half for West Brom before Rams youngster Louie Sibley was harshly sent off in stoppage time for violent conduct.
Derby slipped below Swansea City, who went up to seventh courtesy of a 3-1 win at Birmingham City, with Liverpool loanee Rhian Brewster taking his tally to eight goals in 16 Championship games.
Middlesbrough won for the second time in four games since Neil Warnock was appointed as manager, Britt Assombalonga and Ashley Fletcher on target in a 2-0 success at Millwall.
Wigan, who could yet incur a 12-point penalty having gone into administration last week, climbed eight points away clear of danger for now thanks to Kieffer Moore's first-half strike in a 1-0 victory over QPR.
Elsewhere, Bristol City beat Hull City - who are in the relegation zone - 2-1 and Preston North End came from behind to defeat Sheffield Wednesday 3-1.