Goals in either half from Alessandro Diamanti and Carlton Cole hoisted West Ham out of the relegation zone and eased the pressure, at least temporarily, on the club’s manager, Gianfranco Zola.

The West Ham co-owner David Sullivan had introduced a sub-plot to this game’s main theme – his side’s suitability for the relegation fight – by suggesting that the outcome would also reveal whether he or Zola had been correct about the effects of his decision to announce during the build-up that there will be swingeing pay-cuts at Upton Park. Zola, not a man who is easily stirred to protest, angrily denounced the timing of that declaration, saying it risked denting morale. “I hope it galvanises the team and the manager to produce a wonderful performance,” Sullivan replied. “If we win I have made my point, if we lose he has made his point.”

A point that Zola was probably more determined to disprove was Sullivan’s assertion that he might be “too nice” to thrive as a manager. Sullivan subsequently assured the Italian that he was not in imminent danger of being dismissed, but Zola nonetheless decided it was time to show he was capable of making cold-hearted decisions, dropping Mark Noble and Jack Collison, two youngsters in whom he had hitherto kept faith despite jaded-looking recent performances. As he sought to end a run of six games without a win, Zola also gave a first start to January signing Mido up front, and deployed fit-again Herita Ilunga at left-back, a position where West Ham had been vulnerable during the Congolese’s absence.

Birmingham manager Alex McLeish had been forced to alter his line-up for the first time in 13 Premier League matches, the most notable of his three changes being the selection of the veteran striker Kevin Phillips for the injured Christian Benítez, but his team retained the compactness that has made them so difficult to infiltrate this season. West Ham began buoyantly, betraying no trace of concern about future earnings, but for all their earnest interplay they struggled to prise the visitors apart. Two tame efforts from Mido and a decent shot over the bar from Diamanti were all they mustered by way of goalscoring opportunities in the opening half an hour.

After absorbing early pressure Birmingham grew as an attacking force. Cameron Jerome should have put them in front in the 29th minute but shot wide after the ball broke to him at the edge of the box. That drew a response from the hosts, and Cole, after cleverly creating space for a shot in the box, cracked the ball just wide two minutes later.

Seconds before half-time the home side got the breakthrough they craved. The impressive Scott Parker pierced the visiting defence with a strong run before being brought down on the edge of the box by Scott Dann. Diamanti curled the free-kick into the top corner.

Diamanti was also responsible for the first threat of the second half, skipping past two opponents in the 55th minute before testing Joe Hart with a bobbling shot from 25 yards. Hart did not fail.

West Ham were brimming with confidence now, however, and added a deserved second goal in the 67th minute. Julien Faubert, venturing forward for the first time in the evening, created the chance with an overlapping run down the right and a cross to the near post that Cole met with a well-directed header.

Though West Ham spent most of the rest of the game seeking a third goal, they defended valiantly on the few occasions it was required. Matthew Upson blocked a close-range shot from Jerome in the 80th minute. That was the clearest opening Birmingham could forge as West Ham’s defence and midfield, in which Parker was outstanding, worked diligently to deny their opponents space to create. This alert, powerful performance represented a substantial improvement on listless recent outings. It seemed the home players were galvanised. Leave it to Zola and Sullivan to determine what by.

Premier LeagueWest Ham UnitedBirmingham CityPaul Doyleguardian.co.uk