Birmingham - Birmingham midfielder Lee Bowyer pushed 10-man West Ham into the relegation zone as the former Hammers star continued his free-scoring form in a 1-0 win on Saturday.
Bowyer scored just five times in his three-year spell with West Ham before leaving Upton Park in pre-season, but the 32-year-old is in fine fettle at Birmingham and took his goal tally for the season to six with a clinical strike early in the second half at St Andrews.
His third goal in four games gave Birmingham a fourth successive league win to equal their best top-flight run for five years.
Gianfranco Zola's team, now 18th in the table, had midfielder Mark Noble sent off in the closing stages and were unable to avoid a third defeat in five games.
Birmingham were on top early on and Roger Johnson's flick forced an excellent close-range save out of England goalkeeper Robert Green.
Bowyer got on the end of a low cross from Cameron Jerome after starting the move himself but failed to make proper contact on his shot which flew wide of the far post.
West Ham came more into the game after the half-hour mark and Alessandro Diamanti twice went close in the space of 30 seconds.
Junior Stanislas was adopting a shoot-on-sight policy and Joe Hart went down to his right to keep out a long-range effort which took a slight deflection.
Jerome should have done better in first-half injury-time when heading over from a Liam Ridgewell cross.
But Bowyer broke the deadlock after 52 minutes. Jerome and Christian Benitez combined before the ball was threaded through to Bowyer and he drilled the ball past Green.
Birmingham came close to doubling their lead when Benitez released Jerome in space inside the box and his rising shot was turned aside for a corner by Green.
Ridgewell then turned the ball wide at the far post after Jerome had flicked on another dangerous inswinging free-kick from Sebastian Larsson.
Kieron Dyer almost made an instant impact, cutting in from the left flank and seeing his shot crash against the far post.
Noble was booked for a push in the back on Bowyer and saw red in the 79th minute when he brought down Benitez.