Goals from Joe Cole, Nicolas Anelka, Frank Lampard and Deco gave the Londoners their seventh victory in a row on the opening day of the season and the newly-installed Brazilian coach the ideal start to his Stamford Bridge reign.
The early exchanges were of the nip and tuck variety, but Chelsea counter-attacked well on 10 minutes with Lampard, Deco and Anelka all playing incisive one-touch football.
The unfortunate thing for the Blues was Anelka's woeful shot which sailed high and wide of the Portsmouth goal.
Two minutes later and Chelsea hit the back of the net through Joe Cole, who beat the offside trap and latched onto Michael Ballack's defence-splitting curved right-footer.
The England midfielder raced into the penalty area and slotted a low right-footer wide of David James and into the right-hand corner of the net.
Anelka should have hit his first goal of the season on 18 minutes, but his low drive from just inside the area was well parried by James.
Chelsea's second goal came on 26 minutes when new boy Jose Bosingwa zipped down Portsmouth's left flank and crossed the ball deep to the far post.
Deco and Ballack charged in but it was Deco's clipped left footer which was met forcefully by Anelka who, two yards out and in the centre of the goal, out-jumped James and nodded the ball into the net.
The Frenchman almost hit his second three minutes later after racing onto a long ball. He clipped the ball past James but over-hit his touch and the ball fell away from him for a goal-kick.
Just before this, Younes Kaboul hit a 25-yard free-kick into the back row of the Matthew Harding Stand so bad was the effort.
Ballack lasted just 38 minutes of the game before he was replaced by Florent Malouda after picking up a knock.
Petr Cech was forced into a double save three minutes from the break. He spilled the long-range effort from Niko Kranjcar but stood up well to stop Peter Crouch's follow-up effort.
Chelsea notched up number three from the penalty spot on 45 minutes.
Joe Cole drove in the ball from just inside the penalty area and Sylvain Distin was unlucky to see it hit his left hand.
Up stepped Lampard to drill the ball home, sending James the wrong way in the process.
Within minutes of the restart, Anelka and Joe Cole had chances to increase the lead but both shot just wide.
Portsmouth enjoyed their best spell of the game as the counter opened up.
It took until the 77th minute for the Crouch and Defoe combination to work with the former heading on for the diminutive striker to slice his volley wide of goal.
Seconds from the end and man-of-the-match Deco unleashed a ferocious 30-yard shot which James could only parry into his net as Chelsea finished the match in style.