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A controversial penalty proved to be the turning point as Birmingham came from behind to beat West Brom 3-1 at St. Andrew’s.

Cedric Kipre’s clumsy lunge on Koji Miyoshi was deemed a spot-kick by referee James Linington and Juninho Bacuna equalised in the 23rd minute.

From that moment, John Eustace’s side did not look back and Dion Sanderson headed Blues in front in the 38th minute before substitute Gary Gardner grabbed a third with an 87th-minute free-kick.

That seemed a long way off in the sixth minute when John Swift put West Brom ahead with his sixth goal of the season.

The 28-year-old forward coolly passed the ball into the net first time from 20 yards from Grady Diangana’s square ball, the shot going in off the post.

The timing and precision of the strike meant goalkeeper John Ruddy had no chance of saving Swift’s second goal of the week.

Some City fans thought they had equalised in the 12th minute but Miyoshi’s shot ripped high into the side netting from a tight angle after Jay Stansfield headed Juninho Bacuna’s corner across goal.

Birmingham were level in the 23rd minute with a penalty which was hotly disputed by West Brom’s players.

At first glance the decision looked harsh as Miyoshi was falling anyway before Kipre’s lunge on him, but there was a follow-through from the latter which presumably made up the mind of referee Linington.

Bacuna made no mistake from the spot for his first Championship goal of the season, sending his kick low to the left of Alex Palmer, who dived the opposite way, and perfectly inside the post.

In a typical derby, action swung from end to end and a bouncing header from West Brom’s Alex Mowatt was held by Ruddy.

But it was Blues who dominated the rest of the half. The lively Bacuna saw a low shot deflect just wide off Kyle Bartley before John Eustace’s side took the lead in the 38th minute.

Sanderson guided a header high into the net from Cody Drameh’s deep cross after West Brom partly cleared a corner.

Sanderson, the former Wolves academy graduate, ran in front of the West Brom fans to celebrate enthusiastically.

West Brom wasted a golden chance to equalise in the 59th minute. Darnell Furlong slid in unmarked at the far post to meet Matt Phillips’ cross but his shot from six yards out flew inches wide.

Furlong had another chance soon afterwards but his far-post header flew straight at Ruddy.

But Blues need not have worried as Gardner curled home a delightful free-kick to seal Blues’ second home win in a week after Kipre was booked for bringing down substitute Scott Hogan in the D.