Martins, second from the right, scored his first goal for Birmingham
Birmingham eased into the last eight of the FA Cup with a convincing win over Sheffield Wednesday.
Jean Beausejour swept home Lee Bowyer's cut-back after only six minutes, following good work by Alexander Hleb.
Obafemi Martins scored his first goal for Birmingham before David Murphy scored from close range in the second half to ensure Birmingham's progress.
The Owls did their best to fight their way back into the game but were unable to penetrate the home defence.
But Birmingham's win was tempered by an injury to Hleb.
The Belarusian set up the first two goals for Beausejour and Martins but was then stretchered off and looks doubtful for next weekend's Carling Cup final against his former club Arsenal.
Hleb's vision was vital to Birmingham's opener, picking out Lee Bowyer's late run, allowing the former England midfielder to send the ball across the danger area towards Beausejour.
The Chilean was unmarked as he side-footed the ball past Nicky Weaver.
It came as no surprise when Martins, on loan from Rubin Kazan until the end of the season, scored his first goal for the club in the 17th minute.
Hleb was again the creator with a pass that Martins was able to take into his stride before firing past the exposed Weaver into the far corner of the net.
But Hleb's afternoon came to a premature end after he was chopped down by James O'Connor, with David Bentley coming off the bench to replace the playmaker.
Owls boss Gary Megson, still without a win since taking over at Hillsborough, made a defensive change after 27 minutes with Richard Hinds replacing Mark Reynolds - but it did little to prevent wave after wave of Birmingham attack.
Cameron Jerome spurned a great opportunity to make it 3-0 when he prodded wide from three yards after a low Bentley cross to the near post.
Wednesday had a couple of chances to capitalise on their best spell of the game late in the first half but Neil Mellor just failed to connect with a low cross from Daniel Jones after he had got past Stephen Carr.
Megson made two more changes at half-time with Mark Beevers and Liam Palmer replacing Michael Morrison and O'Connor.
These changes appeared to have stiffened the visitor's defence but only eight minutes into the second half Birmingham went further ahead through Murphy.
Weaver punched away Keith Fahey's corner to the near post under pressure from Bowyer but Murphy was first to react and drilled his shot home.
That goal effectively ended the game as a contest but Martins missed a good opportunity to make it 4-0, firing over the bar from close range.
Sheffield Wednesday toiled for a consolation but the gulf in class between the teams was, ultimately, too great for the League One side to bridge.
Birmingham manager Alex McLeish:
"In terms of allowing players to recharge batteries and being able to change the team, it was a good day for us.
"It was good for some players to come in and get some much-needed match practice."
Sheffield Wednesday manager Gary Megson: "If someone scores a world-class goal against you, or a lucky one, there is not a huge amount you can do.
"But the first goal is an awful one to give away. It starts on the halfway line and is a ball we should clear and be a lot stronger with.
"Next time we are touching the ball, it is in the back of the net. The second goal is even worse."
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