Monk hit out at Pep Clotet on the eve of the match, accusing his former assistant of being "disloyal" for succeeding him as Birmingham's interim head coach in June.
The game finished all square after Kadeem Harris cancelled out Alvaro Gimenez's goal nine minutes from time at Hillsborough.
Elsewhere, West Brom regained top spot with a comfortable 4-1 victory over Bristol City.
Slaven Bilic's men cruised to all three points at The Hawthorns to leapfrog Leeds United, who had climbed to the summit with a late win at Reading 24 hours beforehand.
Preston North End lost ground on the automatic promotion places with a heavy 4-0 loss at Hull City, while Nottingham Forest put four unanswered goals of its own past QPR.