There are moments in every Premier League season that can be seen as defining. Whether it is a win against the odds for a struggling team to catapult them to a run of survival form or even a scrappy win to inflict defeat on a close rival. In a Premier League season won by just a single point, this was certainly Chelsea's defining moment.

Before the Blues hosted Manchester United on this day in 2009 the two teams were vying for top spot. Chelsea were two points clear of both United and Arsenal, which meant that an away win would see United leapfrog their opponents. A home win, however, would give Chelsea breathing room. A lot was at stake.

For United both Nemanja Vidic and Rio Ferdinand were absent, which left them with a very makeshift defence of Jonny Evans alongside Wes Brown, with John O'Shea at right-back. They were up against Didier Drogba and Nicolas Anelka. On paper at least, the visitors were in for a tough time.

However, United being United were up for the big clash and on any other day probably would have taken the points. Sir Alex Ferguson perhaps saw that his defence would not be able to handle Drogba and Anelka on their own, so he added extra bodies in midfield and made a wall in front of Carlo Ancelotti's intricate diamond of Deco at the front and Michael Essien at the back.

Antonio Valencia and Ryan Giggs were on the wings, tasked with stopping Ashley Cole and Branislav Ivanovic getting forward. In the middle were Darren Fletcher, Michael Carrick and Anderson - the combativeness and tidy passing of the first two paired with the flair of the latter. Fletcher protected the defence, rarely straying from his position and as such neither Deco nor Michael Ballack could get any space or joy.

However, as is so often the case in football, the tactical battle is only half of it. On the pitch, luck and resilience play a part and goals can happen in an instant. Chelsea certainly had good fortune as Wayne Rooney was ruled offside in a very close decision and a slight pull from John Terry on Valencia's shirt. There was more fortune in the eventual winner, too. Fletcher was adjudged to have fouled Joe Cole, which might not have been given, and from it Terry headed his side in front.

Even though the Red Devils were tactically very good on the day, they fell apart all to often when they got near the final third. Most of their chances came from outside the box, with Petr Cech unlikely to be beaten from range. Rooney huffed and puffed and could have scored with two excellent strikes, but United in the end fell to their fifth away defeat from six against the league's big sides.

By the end of the season, this result would prove very important in the destination of the title. Chelsea ended with a record 103 goals, but claimed their third Premier League title by just the one point. It went down to the final day and Chelsea may well look back on this day being the one that they believed they could take the title back from United.