Manchester United will look to rectify the Achilles heel that cost them an historic fourth successive title last season when they visit Chelsea on Sunday. Last term the Reds were beaten 1-0 at Stamford Bridge in November and then lost 2-1 to Carlo Ancelotti's side at Old Trafford in April. That double whammy effectively enabled Chelsea to win the Premier League trophy by a point. Now the Reds have the chance to go six points clear of their title rivals with a game in hand if they win at Stamford Bridge and pour more misery on what has been a sorry run for the Londoners. Having claimed Arsenal's scalp on Monday night, former skipper Rio Ferdinand now believes more heavyweight victims are a must if United are to win the league. Winning against Arsenal is a big result, said the defender, who was at the heart of United's superb defensive performance against the Gunners. It is not a defining result for the season but it is a big result against one of the teams at the top of the table. Last year we probably didn't do as well against the big teams as we should have. This was a good way to start. It would be lovely if we got the same result on Sunday at Chelsea. To win titles you have to be on top form all the time. It is not just about defending as a back four and a goalkeeper, we score together and we concede together. If we are defending right from the front we will be a hard team to play against. It is only in recent weeks against Blackburn and Arsenal that United have found their top gear. Up to the end of November both fans and critics alike were surprised that the Reds were challenging at the top despite struggling to hit form. But the fact they look like being No 1 at Christmas has not shocked Ferdinand. I would have believed it, he said. When I look around the changing room I see a fantastic bunch of players. I never doubt our players or what we are capable of. If we concentrate and are focused on doing the things we are asked, we are difficult to play against. Victory over Arsenal, which came courtesy of a Ji-sung Park first-half header, extended United's unbeaten start to 16 matches, a new club record. It is not about trying to go through the season unbeaten, said the England skipper. It is about what you finish up with at the end of the year. Will United beat Chelsea? Have your say.