LONDON, Dec. 26 (Xinhua) -- Chelsea failed to break their under-par jitter on Saturday as the Premier League leaders, grabbing one win out of last five, were held to 0-0 at Birmingham City in holiday fixture.

    Birmingham goalkeeper Joe Hart produced a string of fine saves to frustrate the visitors, extending his side's unbeaten league run to 10.

    Hart, who ended the match with a bandaged head, denied Daniel Sturridge and Frank Lampard in the first half but was rescued by his crossbar when Brazilian defender Alex unleashed a thumping free kick.

    Birmingham had the ball in the net in the first half but Cristian Benitez was ruled offside when he tapped in from close range. Television replays suggested he was being played on by a grounded Didier Drogba.

    Gianfranco Zola's West Ham United climbed out of the relegation zone with a 2-0 home win over Portsmouth.

    Tottenham Hotspur remained in fifth place after a 0-0 draw at Fulham and the points were also shared at Sunderland, who drew 1-1with Everton.

    Wigan Athletic also tied Blackburn Rovers 1-1. The same happened to Burnley's home match with Bolton Wanderers. Roberto Mancini began his reign as Manchester City manager with a 2-0 home victory over Stoke City.

    Chelsea moved five points clear of champions Manchester United despite failing to score for the first time in 34 league games.

    United can narrow the gap at Hull City on Sunday. Liverpool face Wolverhampton Wanderers later on Saturday.