Two Didier Drogba strikes and an own goal from Abel Xavier were enough to give Chelsea victory against Middlesbrough at Stamford Bridge.
Drogba was a thorn in Boro's side
Drogba opened the scoring when he curled in a low 20-yard free-kick.
Xavier poked in Arjen Robben's driven ball, before Drogba added his second with a free-kick that looped in following an Andrew Davies deflection.
Boro's best chance came in the opening moments of the game when Mark Viduka headed wide from six yards.
The visitors more than matched their esteemed Premiership rivals for much of the opening half and were unlucky to go into the break a goal down.
Arguably, the best chance of the 45 minutes fell to the visitors when Viduka, somehow headed wide from six yards after connecting with Andrew Taylor's left-wing cross.
His strike partner, Yakubu, also caused the Chelsea defence - minus Ricardo Carvalho - problems.
The bulky Nigeria forward sprung the offiside trap and took the ball into the area before cutting back only to see keeper Petr Cech palm the ball away and deprive Viduka of a shot on goal.
Chelsea duo Drogba and Andriy Shevchenko also looked lively, although they did not work as well in tandem as their rival pairing.
Individually, Shevchenko and Drogba were a joy to watch. Ukraine's star striker created one piece of sublime trickery on the touchline to beat two Boro markers and also struck a shot from 25 yards that flew two yards wide.
Drogba also saw two fierce efforts fly narrowly wide early in the half, before finally hitting the target when his side-footed 20-yard free-kick broke through the flimsy Boro wall to beat the dive of Schwarzer.
Boro came close to levelling the scores midway through the second half when Yakubu's jinking run ended with a scooped shot over the bar.
The striker and the rest of Gareth Southgate's team were left to rue that miss, when Portuguese defender Xavier inadvertantly deflected substitute Robben's driven ball past the helpless Schwarzer.
Robben, who had been out for four games with an ankle injury, had only been on the pitch for a minute after coming on to replace the injured Lassana Diarra.
Chelsea rounded off the scoring late in the game when Drogba, with the aid of Davies' shoulder, scored his 25th goal of the season from a set-piece on the left-corner of the 18-yard box.
Chelsea manager Jose Mourinho:
"I wanted Chelsea to win and win and win and, in the main, that is what we have done. Now we must keep on doing it.
"Credit to United, they're doing it too. We're in a battle. We can't afford not to keep winning, neither can they.
"We're enjoying it. To go on enjoying it, we must keep on winning."
Boro boss Gareth Southgate:
"Drogba's goal on the stroke of half-time was the turning point of the game. We would have been good value to have gone in level.
"That was disappointing. We gave a decent account of ourselves but not as well as we have been playing.
"The run we've had has been great. The players have given me everything."
Chelsea: Cech, Diarra (Robben 65), Ferreira, Terry, Bridge, Essien, Makelele, Lampard, Kalou (Wright-Phillips 85), Drogba, Shevchenko (Geremi 88).
Subs Not Used: Cudicini, Boulahrouz.
Goals: Drogba 45, Xavier 66 og, Drogba 83.
Middlesbrough: Schwarzer, Davies, Xavier, Pogatetz, Taylor, Morrison (Euell 73), Boateng, Arca (Rochemback 84), Downing, Viduka (Christie 84), Yakubu.
Subs Not Used: Jones, Hines.
Ref: C Foy (Merseyside).