Leicester moved back to the top of the Championship after coming from behind to beat Millwall 3-2 on Wednesday.
Tom Bradshaw's opener put the Lions in front at halftime at the King Power.
But Leicester fought back as three goals in 30 minutes from Jannik Vestergaard, Patson Daka and Ricardo Pereira ensured Enzo Maresca's men edged one point above Ipswich.
The top two now enjoy a 10-point cushion in the automatic promotion places after Southampton missed the chance to leapfrog Leeds into third.
The Saints were held 1-1 at Coventry as Samuel Edozie came off the bench to cancel out Haji Wright's opener for the home side.
Hull climbed to within goal difference of the playoff places with a 2-1 win at Middlesbrough.
Boro led at halftime courtesy of Emmanuel Latte Lath's seventh goal of the season in the sixth minute, but Liam Delap and Ozan Tufan struck in the second half to lift the Tigers up to seventh.
Wayne Rooney enjoyed his first away win as Birmingham boss thanks to Juninho Bacuna's goal in a 1-0 victory at Cardiff.