Birmingham leaped out of the Premier League's bottom three with a crucial win over fellow strugglers West Ham. Nikola Zigic scored the only goal of the game when he headed in Sebastian Larsson's free-kick on 65 minutes. West Ham's Demba Ba came off the bench and also almost marked his debut with a goal but his shot hit the post. Birmingham had their defence to thank for a clean sheet, although they were lucky to escape when Manuel da Costa shot off-target and then headed wide. The hosts went close on several occasions with Victor Obinna and Robbie Keane impressive in the first half, yet they had trouble carving out many clear openings and the defeat leaves them at the bottom of the Premier League on goal difference, two points from safety. It is a huge blow for the Hammers after encouraging displays in their last two games where they beat Blackpool and Nottingham Forest in the FA Cup. Birmingham were also victorious the last time these two teams met, thrillingly overturning a deficit in the second leg of the Carling Cup last month. But with both sides in the Premier League's bottom three before the game began, the three points at stake made for a cagey match. West Ham were the more threatening to start with Obinna, fresh from five goals in his last two games, at the heart of much of the hosts' good work. The Nigerian forward lined up on the left of a front three with Keane in the middle and Frederic Piquionne on the right, and it was from Keane's lay-off that the former Portsmouth striker curled a shot straight at Ben Foster on 20 minutes. The Irishman's ability to hold the ball up and find space in congested central areas was a help to Avram Grant's side, and his lay-off allowed Obinna to shoot left-footed but he was off-target. For Birmingham, David Bentley attacked with purpose on a couple of occasions and shot over early on, but Alex McLeish's midfield were struggling to link up with the front pair of Zigic and Cameron Jerome. Roger Johnson came closest to scoring for the visitors in the first half when he headed over from six yards following Lee Bowyer's cross, but he made up for that by producing some sterling defending to head clear Obinna's bullet centre. Grant had to make a last-minute change to his starting line-up with Matthew Upson replacing the injured James Tomkins in the heart of the defence but Upson, himself, could only last until half-time. Da Costa replaced the England defender and it wasn't long before he was under pressure when Bentley found Zigic but the Serbian's header was wide. McLeish then made what looked like a negative decision to take off Jerome and replace him with midfielder Larsson just before the hour. But the Swede justified the faith his manager showed in him when his set-piece from the left was headed in at the back post by Zigic - his sixth goal of the season. West Ham argued that the free-kick awarded to Birmingham was a soft one, with Mark Noble barging over Bentley, but the appeal emphasised the growing frustrations of the West Ham supporters. The hosts had several penalty shouts too but, in truth, referee Chris Foy was about right to deny them, including a push on Keane and handballs where the ball struck Birmingham defenders from point-blank range. Grant had to make a last-minute change to his starting line-up with Matthew Upson replacing the injured James Tomkins in the heart of the defence but Upson, himself, could only last until half-time. Da Costa replaced the England defender and it wasn't long before he was under pressure when Bentley found Zigic but the Serbian's header was wide. McLeish then made what looked like a negative decision to take off Jerome and replace him with midfielder Larsson just before the hour. But the Swede justified the faith his manager showed in him when his set-piece from the left was headed in at the back post by Zigic - his sixth goal of the season. West Ham argued that the free-kick awarded to Birmingham was a soft one, with Mark Noble barging over Bentley, but the appeal emphasised the growing frustrations of the West Ham supporters. The hosts had several penalty shouts too but, in truth, referee Chris Foy was about right to deny them, including a push on Keane and handballs where the ball struck Birmingham defenders from point-blank range. Source: BBC