( CNN ) -- Portsmouth will play Chelsea in the FA Cup final after an upset 2-0 extra-time victory over Tottenham Hotspur in the second semifinal at Wembley on Sunday . French striker Frederic Piquionne opened the scoring for Avram Grant 's men nine minutes into extra-time . Former Tottenham midfielder Kevin-Prince Boateng scored the second with three minutes remaining from the penalty spot after referee Alan Wiley awarded a spot kick as Wilson Palacios fouled Aruna Dindane . It was a humiliating defeat for Tottenham and their manager Harry Redknapp , who steered Portsmouth to FA Cup triumph in 2008 before leaving the cash-strapped club for White Hart Lane . His team went into the match as overwhelming favorites against a Pompey team who had been relegated from the Premier League the day before without playing , having been deducted nine points after going into administration . But all that was forgotten as their fanatical fans enjoyed a famous victory which owed much to good fortune and some excellent goalkeeping from England international David James . Their breakthrough goal could be credited to the appalling Wembley pitch as Spurs defender Michael Dawson slipped at a crucial moment and Piquionne took full advantage . Tottenham thought they had equalized almost immediately through Peter Crouch but Wiley ruled it out for a push on James . With Tottenham camped in the Pompey half , Dindane broke clear and although Palacios got the ball in his challenge he also pulled him down and Wiley had no hesitation in pointing to the spot . Spurs reject Boateng scored past Heurelho Gomes with relish to seal a famous cup victory . An overjoyed James said they had deserved their win after being written off before the semifinal . `` We played very well throughout the team , he told ITV . `` Look what it means to Pompey , it 's fantastic . `` We were eight- or nine-to-one to win beforehand but we have proved people wrong . '' In truth , Tottenham had been the more accomplished side in a generally scrappy match and Crouch will be rueing a headed miss against his former side in the second half in which he also hit the post . Aaron Mokoena had to make a goalline clearance from a Vedran Corluka cross in Tottenham 's best spell of pressure , but Pompey were always a threat on the break and took their chances when offered . They will play double-chasing Chelsea at Wembley on May 15 and again will start as massive underdogs .
Portsmouth beat Tottenham Hotspur 2-0 in FA Cup semifinal at Wembley . Goals from Frederic Piquionne and Kevin-Prince Boateng seal famous win . Portsmouth will play Chelsea in final at Wembley on May 15 .