Didier Drogba struck his 29th goal of the season as Chelsea won a hard-fought game at Portsmouth to keep the Premiership title race alive.
Drogba's winner was his 18th in the Premiership this season
Drogba struck the opener just after the half-hour mark, volleying Ashley Cole's left-wing cross into the ground and past Portsmouth goalkeeper David James.
Pompey enjoyed plenty of possession, but Andy Cole and Kanu both saw headers magnificently saved by Petr Cech.
Salomon Kalou wrapped it up, sliding in after Ashley Cole's header forward.
Manchester United's win at Liverpool earlier in the day made victory imperative for Chelsea, as they sought to keep United's lead at the top to nine points.
The Pompey fans were revelling in Chelsea's deficit, as chorus after chorus of 'Where's your title gone?' rang around Fratton Park as the game kicked off.
Pompey looked lively too, no-one more so than the unplayable Kanu, who was winning everything in the air and providing a classy lesson in hold-up play to boot.
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Kanu and Lomana LuaLua were giving Chelsea a real headache, but the visitors were using their pace on the break as the game swung from end to end.
Andriy Shevchenko was brilliantly played in down the left by Arjen Robben, but the Ukraine international - without a goal in the Premiership since 11 November - blazed hopelessly over.
Since Shevchenko's last league goal Drogba has scored nine and after he blazed woefully wide from his strike partner's clever pass, the newly-crowned African Footballer of the Year gave the visitors the lead.
Peeling away at the back post, Drogba met Ashley Cole's cross from the left to volley into the ground and past James.
Seconds after the restart, the champions wasted a fabulous chance to wrap up the points.
Robben played a sumptuous one-two with Drogba but instead of passing across the six-yard box to the unmarked Shevchenko, he shot against the post and Pompey survived.
It was shaping up to be a classic Chelsea performance away from Stamford Bridge, the sort of slender, battling win that hallmarked their two recent championship successes.
Claude Makelele and Michael Essien were magnificently keeping the Pompey attack at bay, with Essien at centre-back once more admirably stepping into the absent John Terry's shoes.
When Portsmouth did manage to breach the Blues' defence, they found Cech in world-class form between the posts.
He wonderfully stuck out his left hand to save a goalbound Andy Cole header, before flying low down to his right to parry away Kanu's nodded effort.
Cech's heroics were not in vain, as Chelsea raced up the other end and Ashley Cole headed into the box for substitute Kalou to slip past the advancing James.
Portsmouth boss Harry Redknapp:
"We played well and I was disappointed to be 1-0 at half-time.
"In the second half we were a lot stronger and I thought there was an equaliser there, but the keeper has pulled off a couple of fantastic saves.
"We got caught pushing forward for their second, but overall I was very happy with the players."
Chelsea manager Jose Mourinho:
"Our job is to keep winning matches and get back to six points (behind Manchester United) and have the pressure on them.
"We have to win all our matches and wait for them to drop some points.
"It was a big victory today and no injuries. That is almost unique this season."
Portsmouth: James, Pamarot, Primus, Campbell, Traore (Kranjcar 68), O'Neil, Davis, Hughes, Taylor, Kanu, LuaLua (Cole 73).
Subs Not Used: Ashdown, O'Brien, Mvuemba.
Chelsea: Cech, Diarra, Carvalho, Essien, Ashley Cole, Makelele, Lampard, Ballack, Robben (Wright-Phillips 76), Shevchenko (Kalou 76), Drogba (Bridge 84).
Subs Not Used: Cudicini, Ferreira.
Booked: Ballack, Makelele.
Goals: Drogba 33, Kalou 82.
Ref: M Halsey (Lancashire).