Super-sub Webber rescues Pompey
Portsmouth substitute Danny Webber notched his first Premier League goal for the club to keep Avram Grant's side in touch with their relegation rivals.
The Hammers held basement team Pompey at Fratton Park, with Matthew Upson giving the visitors the lead after 52 minutes.
But Webber's 75th-minute goal just two minutes after replacing Frederic Piquionne kept his side's hopes of survival alive.
The game exploded into life after 20 minutes when Asmir Begovic made a double save, first parrying Frank Nouble's effort and then diverting Valon Behrami's follow-up wide.
At the other end Robert Green needed to be at full stretch to turn a drive from John Utaka wide.
Jack Collison forced Begovic into another save but the game remained scoreless at the break.
Seven minutes into the second half Upson gave West Ham the lead when Alessandro Diamanti's cross found his skipper, who leapt high and diverted the ball past Begovic with his chest.
Grant introduced striker Webber for the final 17 minutes, and the ex-Manchester United man made an instant impact.
Kevin-Prince Boateng headed the ball down for Utaka, who slotted Webber in beautifully to coolly slot past Green.
Webber nearly doubled his tally after 81 minutes, when he flicked Utaka's cross just over the bar but the Hammers held on.