A minute later Chelsea captain John Terry headed the ball against the bar again with James beaten.
Portsmouth rode their luck once more 10 minutes later when James pushed Didier Drogba's rasping 30-metre free kick against the bar, and was fortunate to collect the ball after it had bounced down on the line.
The right-hand post came to Portsmouth's rescue again two minutes later when Drogba cracked the ball against it from close range with England goalkeeper James again beaten.
The Ivorian striker showed his utter frustration by smacking the post with his hand and then leapt up to hit the bar too.
Chelsea had four other chances but despite being in control they had needed a stunning reflex save from Petr Cech to save a close-range effort from Frederic Piquionne after 22 minutes.
(Editing by Ken Ferris To query or comment on this story email firstname.lastname@example.org)