Frank Lampard grabbed the only goal of an open encounter to end Portsmouth’s unbeaten start to the season and send Chelsea top of the Premier League.
Claudio Pizarro squandered two fine chances before Lampard burst onto Didier Drogba’s exquisite back-flick and drilled the ball under David James.
But Pompey also created plenty and Matt Taylor shot narrowly wide.
And in the final moments Ashley Cole was forced to clear Hermann Hreidarsson’s header off the line.
Chelsea began brightly on a scorching day and Pizarro almost justified his inclusion at the expense of Salomon Kalou within a minute but he dragged his shot wide from the edge of the box.
Florent Malouda then fizzed an effort into the side-netting after a surging run by Michael Essien.
And Pizarro had his second excellent chance of the game but headed wastefully over from Malouda’s perfectly delivered inswinging free-kick.
But after a nervy opening spell the visitors settled and they started to threaten.
