Nottingham Forest beat bottom club Barnsley 3-0 to move with a point of the play-offs following a third straight Championship win.
Forest took the lead in the 15th minute when on-loan Aston Villa forward Keinan Davis slotted home his first goal for the club.
Ryan Yates added a second shortly before half-time and Brennan Johnson wrapped things up with a third in the 75th minute.
Birmingham came from two goals down to fight back and draw 2-2 against relegation battlers Peterborough at St Andrew's.
Jack Marriott broke the deadlock in the 16th minute and Jonson Clarke-Harris slotted in a second-half penalty to briefly move Posh level on points with 21st-placed Reading.