Watford climbed to second in the Championship with a 2-1 win over Derby, while promotion rivals Hull crashed to a 4-1 defeat at Bolton on Saturday.
With leaders Cardiff playing at Wolves on Sunday, Gianfranco Zola's side took possession of the second automatic promotion place thanks to Matej Vydra's 20th goal of the season and a Joel Ekstrand strike.
Vydra's superb effort sent the Hornets into half-time ahead and Ekstrand netted to double the lead midway through the second half.
Jamie Ward soon reduced Derby's deficit to a single goal again from the penalty spot.
The Rams pushed for an equaliser but could not significantly test teenage goalkeeper Jonathan Bond, who was making his first league appearance for Gianfranco Zola's side after Manuel Almunia went off injured at the end of the first half.
Watford are above third placed Hull on goal difference after Steve Bruce's team were routed at the Reebok Stadium.
Dougie Freedman's Bolton raced into a 3-0 lead inside eight minutes at the Reebok Stadium with goals from Darren Pratley, Mark Davies and Craig Dawson.
Robbie Brady gave Hull a late glimmer of hope after 68 minutes but that was quickly killed off as Dawson grabbed his second.
Crystal Palace stayed fourth despite slipping to a late 1-0 defeat at Sheffield Wednesday, who took the points thanks to Leroy Lita's headed winner in the 81st minute.
Fifth-placed Leicester were forced to settle for a 0-0 draw at Blackpool after New Zealand striker Chris Wood fired a penalty against the crossbar for the Foxes.
Brighton improved their play-off chances as a David Lopez goal earned them a 1-0 home win over Burnley.
Nottingham Forest kept themselves in contention as they beat 10-man Charlton 2-0 at The Valley.
Radoslaw Majewski and Henri Lansbury struck in the second half for Forest, now unbeaten in three games under Billy Davies, after the Addicks had Yann Kermorgant dismissed for kicking out at Greg Halford.
Bristol City moved off the bottom of the table after a remarkable 5-3 win over FA Cup quarter-finalists Barnsley.
Two goals from Jon Stead and further efforts from Liam Fontaine and Lewin Nyatanga all but put the game beyond the Yorkshire side.
Chris O'Grady pulled one back but Steven Davies added the Robins' fifth before consolation efforts from Tomasz Cywka and Jason Scotland.
Peterborough slumped back to the bottom after a 2-0 loss at home to Birmingham, while Blackburn drew 0-0 with Leeds and Huddersfield and Ipswich shared a goalless draw.