Crowded out: Dimitar Berbatov looks on forlornly as Chelsea players celebrate Didier Drogba's goal which ultimately secured a 2-1 win over Manchester United at Old Trafford and helped claim the advantage in the title race

There was a theory put forward after Chelsea's Champions League exit last month that the mental torture inflicted by the defeats at the hands of Inter Milan would be outweighed, over time, by the physical boost they would benefit from not having to play twice a week during the season's run-in. However, what wasn't mentioned after that game was the possibility that Carlo Ancelotti might have learned a tactical lesson from Jose Mourinho's shackling of Chelsea on the night and that was as much a factor at Old Trafford yesterday.

The London side, particularly early on, dominated Manchester United by playing at a tempo that the home side just couldn't deal with but Ancelotti's recent tactical re-think was just as important. Where the Italian used to play Didier Drogba and Nicolas Anelka together up-front come what may, he has taken to selecting one of them up-front and playing Florent Malouda and Joe Cole in supporting roles. It has given Chelsea a new lease of life, allowing them to hold onto the ball more effectively and, at the same time, pose a more obtuse and less predictable threat in the final third. It was crucial part of yesterday's seismic victory.

Cole's delightful flicked goal on 20 minutes was just reward for the visitors' early dominance and, while United did come back into the game in the period immediately after half-time, they never really peppered the Stretford End goal. Substitute Didier Drogba, who wasn't judged fit enough to start, walloped in a goal from an offside position to make it 2-0 on 79 minutes and, while Federico Macheda grabbed one back with his hand shortly after – without knowing much about it, admittedly – Chelsea deservedly held on for victory. They now sit two points ahead of United at the top of the table and with a goal difference four superior to the Reds, and can probably afford to draw one of their remaining five games and still claim the title.

"Chelsea are favourites, there's no question of that," said Alex Ferguson after the game. "I have no doubt we'll respond to the defeat but even if we win our remaining five games we might not win the league." Those comments could well be designed to heap pressure on Chelsea in the coming weeks but, aside from all that, they are quite plainly true. Ancelotti's side face Bolton, Stoke and Wigan at home between now and the season's end, as well as Tottenham and Liverpool on the road and, while those away fixtures provide ample room for error, in their current form it is difficult to see Ancelotti's side dropping too many points.

Particularly if they play as well as they did in yesterday's first-half. There was a sharpness to their passing that constantly kept United on the back-foot and their intent to go for it early-on was quite visible. They didn't exactly pin the home side inside their own box but Cole's goal, flicked home cleverly with his back to goal inside the six-yard box following a great run and cross from Malouda, was just rewards for their overall dominance.

"Obviously when you play a Champions League game in midweek it takes a lot of energy," said Malouda in reference to United, "and you could see we were fresher in the way we started. We did it deliberately because we knew we had an advantage if we raised the tempo."

United, though, did get their second wind after the half-time break and put their opponents under considerable pressure in the opening 20 minutes of the second-half. Dimitar Berbatov flashed a header wide, Ji-Sung Park rifled a shot over the bar and there were a couple of edge-of-the-box scrambles that Chelsea just managed to clear. But while it was a storm, it was of the whirlwind rather than sustained variety and, with the visitors out the other side of it, Drogba fired home his side's second even though he was a good yard offside from Salomon Kalou's pass.

"A game of this magnitude deserves top refereeing," said Ferguson afterwards. "When I did see Mike Dean's name, I did worry but I'm not going to get into all of that."

You wouldn't have blamed him if he did, particularly when Park was denied a penalty after being tripped by Yuri Zhirkov in the first half, although Dean, who seemed reluctant to point to the spot having done so 16 times already this season, also waved away a legitimate claim from the visitors when Anelka was bundled over by Gary Neville.

So, the Premier League title is now Chelsea's to lose in the coming weeks and while Ancelotti accepted the mantle of favouritism afterwards, he also preached caution. "We have five matches left," he said. "We have to pay attention and keep our focus." With no Champions League to distract them, only a United fan or a fool would back against them.