CHELSEA are determined to push Manchester United all the way before relinquishing their hold on the Premiership crown and they provided further evidence of that commitment by handing Middlesbrough their first defeat of the year.

A brace of free-kicks from Didier Drogba, taking his tally for the season to 25, and an own goal from Abel Xavier kept Chelsea six points behind United at the Premiership summit. The win over Middlesbrough was Chelsea's fifth consecutive success since they lost to Liverpool last month - scoring 14 goals and conceding none in the process.

And here it took Chelsea just six minutes to carve open the Middlesbrough defence when Frank Lampard's stunning pass set up Drogba. The Ivorian sent a thunderous volley just wide of the target and a minute later he again went close when Middlesbrough's defence failed to clear a loose ball. This time though he sent a low left-foot drive just wide of Mark Schwarzer's right-hand upright.

But it was Gareth Southgate's side who were guilty of squandering the best chance when Mark Viduka headed wide from a cross by Stewart Downing in the 12th minute. Middlesbrough went into the game unbeaten in 2007 and they showed enough in attack to worry the champions.

Aiyegbeni Yakubu did well to spring Chelsea's offside trap but he failed to deliver a telling cross as the home defence scrambled back to recover the situation.

Lampard - whose own future at the club continues to come under the spotlight after his agent refused to deny he was on his way to Barcelona in the summer on Catalan radio - was at the heart of all Chelsea's best moves but even he could not deliver an opening strike when presented with a freekick opportunity 25 yards out.

In the 31st minute it was the turn of Salomon Kalou to try his luck when a nice dummy from Drogba gave him the chance to run at the Boro defence.

The Ivorian stepped inside Andrew Davies to engineer a clear shooting opportunity but despite trying to curl his effort into the top corner it missed the target by some distance.

In the 34th minute a challenge by Drogba on Emanuel Pogatetz sparked an ugly touchline confrontation between Mourinho and Boro boss Southgate. The Chelsea coach had to be kept apart from Southgate by the fourth official has he pressed his finger to his lips to indicate he was unhappy with the Boro manager's verbal onslaught to referee Chris Foy. Mourinho then urged Southgate to sit down in the dugout instead of standing in the technical area.

Chelsea were handed a great chance to open the scoring when George Boateng hauled down Lassana Diarra on the edge of the penalty area and they made Boro pay. The free-kick, in a central position, provided Drogba with the perfect opportunity to curl a low drive into the bottom corner.

In the 48th minute, Julio Arca cleared off the line when Andriy Shevchenko met a corner from Lampard and his glancing header seemed destined for the top corner.

Three minutes later though Chelsea had a lucky escape when Andrew Taylor's cross swerved towards the far post, eluded Blues keeper Petr Cech and cannoned to safety off the crossbar.

But Middlesbrough still possessed the capacity to hurt Chelsea and Yakubu came close in the 59th minute when he got on the end of a quick counter-attack by the visitors. Downing's break down the right flank caught Chelsea on the hop and his ball into Yakubu saw the striker fire just over.

In the 65th minute Chelsea opted to replace the injured Diarra with Dutch winger Arjen Robben for his first appearance since injuring ankle ligaments in the defeat by Liverpool at Anfield. It took him just four touches to help put Chelsea further in front a minute later when his run and shot from the right was deflected into his own net by Boro defender Xavier.

And Drogba was not finished either as the Ivory Coast striker completed the scoring in the 82nd minute when another free-kick was deflected over Schwarzer and into the top corner.