Birmingham moved seven points clear of third place in the Championship after recording a comfortable 2-0 victory over Doncaster on Saturday.
Rovers had the first meaningful effort on goal in a scrappy opening 15 minutes and Birmingham goalkeeper Maik Taylor was forced into a full-strength stop to turn a Michael Woods free-kick around the post.
But Blues took a 19th-minute lead when Sebastian Larsson created space on the right and whipped in a high swirling cross which Cameron Jerome nodded powerfully into the bottom corner from 12 yards.
Birmingham's second came after an almighty gaffe from Rovers left-back Gareth Roberts three minutes before the interval.
He tried to lay the ball back to Neil Sullivan with the outside of his boot but did not get enough on the ball and Hameur Bouazza intercepted to score his first goal for the club.