Manchester United boss Sir Alex Ferguson is already looking ahead to this month's "significant" fixtures against Arsenal and Chelsea. While Ferguson's more immediate concern is whether Saturday's Barclays Premier League encounter with Blackpool at Bloomfield Road beats the weather, pre-Christmas fixtures against United's main rivals have taken on greater onus with his side now two points clear at the summit. The Gunners visit Old Trafford on December 13, with the trip to Stamford Bridge following six days later. And as Arsenal and Chelsea meet themselves on December 27, Ferguson accepts it is going to be a crucial period. "You always want to win those games because they are really significant," Ferguson told Inside United. "We have managed to claw ourselves into a position where we are two points ahead of Chelsea, so the game at Stamford Bridge and Arsenal's trip to Manchester will certainly be very important, there's no doubt about that. "We saw that last season - some big decisions didn't go our way in the two matches against Chelsea and they ended up costing us important points." A clear foul by Didier Drogba on Wes Brown was missed by the referee as John Terry tucked home the winner for Chelsea against United at Stamford Bridge last season, a victory that ultimately proved pivotal in the Blues winning the title. Now United have the edge again, even if their momentum has been hit by that shock four-goal Carling Cup reverse at West Ham. Ferguson is certain to make changes, with Wayne Rooney
, Nemanja Vidic, Rio Ferdinand and Dimitar Berbatov - fresh from his record-equalling five-goal haul against Blackburn - set for a recall. United's first visit to Blackpool since 1974 comes at the start of what is always a pivotal period of the season. "You are aware that you have to use your squad well because there are so many games, particularly during that week between Christmas and New Year," Ferguson added. "Three matches in six days is a lot. It is a hectic period but we have the players to cope. "Hopefully we're in the right position come the start of January." What position will United be in at the start of January? Have your say.