James, who watched Paul Robinson drop a real clanger in England's defeat to Germany on Wednesday night, did not enhance his own case when he failed to prevent Lampard's effort from hitting the net.

James is hoping to replace Robinson for England's two European Championship qualifiers against Israel and Russia next month and could ill afford such a blunder in front of Steve McClaren.

Chelsea began in their customary attacking fashion and almost took a first-minute lead when Claudio Pizarro sent a low drive just beyond the reach of James and his right-hand upright.

Portsmouth have never beaten Chelsea in eight meetings since they returned to the Premier League in 2003 and, although they had taken five points from three games prior to their trip to Stamford Bridge, Harry Redknapp's side showed little desire to change that record.

But the visitors did enough to stifle the home side and such was their success that Jose Mourinho spent much of the first half berating his side for not taking the game to their opponents. Pizarro and Florent Malouda has further chances before Chelsea broke the deadlock in the 31st minute thanks to England midfielder Lampard.

The goal owed much to the bravery of Didier Drogba, who collected a kick in the face for his efforts as he found Lampard with a flick-on.

Lampard ran clear of the Pompey defence to drive the ball under James. The England stopper should have done better but, although he got a hand to the drive, he could not prevent it going in.

It was the signal for Chelsea to increase the pace and Shaun Wright-Phillips and Lampard went close before the interval arrived.

Chelsea were in control for most of the second half but Portsmouth had more than one opportunity to equalise - first through Sean Davis, then Gary O'Neill. But Chelsea were luckiest to escape with three minutes left when a header from Hermann Hreidarsson was cleared off the line by Ashley Cole.