New midfield signing Scott Parker wasted no time in starting to repay his expensive transfer fee as Chelsea kept up their title challenge with a solid victory at relegation-threatened Portsmouth.
Parker had made just one previous appearance for Claudio Ranieri's side following his controversial £10million move across London from Charlton last month, but provided the crucial breakthrough in the 17th minute on the south coast.
Romanian star Adrian Mutu was left in acres of space inside the Portsmouth penalty area as he received a sidefoot pass from Parker.
The England under-21 star still had plenty to do after receiving a return ball from Mutu, but he confidently controlled his centre with his right foot before smashing a left-foot volley high into the roof of the net from eight yards out.
Argentinian striker Hernan Crespo, playing his first game since tearing a calf muscle five weeks ago, made the points safe 12 minutes from the final whistle after chesting the ball into an empty net after fellow sub Jimmy Floyd Hasselbaink had hit the crossbar with a lob over goalkeeper Shaka Hislop.
Hasselbaink came close to netting his 100th Premiership goal just minutes later when he shot into the side-netting from a tight angle as Chelsea moved to within one point of second-placed Manchester United in the title race.
But the Londoners by no means had things all their own way at Fratton Park as Portsmouth chased their first league victory over Chelsea since 1957.
Chelsea goalkeeper Neil Sullivan nearly gifted them an equaliser in the 24th minute when his dreadful clearance rebounded off team-mate John Terry into the path of striker Yakubu. But the Nigerian fired over the crossbar with the goal beckoning.
Patrik Berger produced a superb piece of individual skill seven minutes later to rattle Chelsea's woodwork with a 25-yard left-foot shot after he had beaten three defenders while Yakubu forced a good save out of Sullivan on the stroke of half time.
Berger was forced to limp out of the action in the 57th minute with an ankle injury, but his replacement Lomana LuaLua proved equally threatening as he twice went close with long-range efforts before Crespo settled the encounter.