Manchester United midfielder, come emergency centre-back, Michael Carrick has issued an ominous warning to title rivals Chelsea, insisting the champions are just starting to hit top gear.

Sir Alex Ferguson's men have been in impressive form of late as they go in search of an unprecedented fourth successive Premier League title, closing the gap on leaders Chelsea to just two points in the process.

Wins over Everton, Portsmouth and West Ham, scoring 11 goals and conceding just one in the process, over the past fortnight have seen United turn on the style, with Ryan Giggs and Wayne Rooney in particular, in devastating form.

Minus 15 first-team players, United sealed their safe passage into the last 16 of the UEFA Champions League as Group B winners with a resounding 3-1 win over Wolfsburg in Germany on Tuesday evening.

And Carrick insists they are hitting top form just at the right time heading into the busy festive period, although he and his team-mates know from past experience that the title race is a marathon and not a sprint.

"We certainly won't take our foot off the pedal now," Carrick is quoted as saying on skysports.com. "We're starting to play well - and we are scoring some goals, too.

"There's an awful long way to go and we are not getting carried away. But we have been there before and we know what is required. It is about doing the business now."