For the first half of Arsene Wenger's reign at Arsenal the team's clashes with United often went a long way to deciding the destination of the Premier League but the emergence of Chelsea as a major power knocked the Gunners down the pecking order.
They last won the title in 2004 and have not cracked the top two since 2005 but they go into Monday night's game at Old Trafford proudly back on top of the league and bidding for their first win there for four years.
Their key man in recent weeks has been Samir Nasri, who scored both goals in last week's 2-1 win over Fulham and another in the 3-1 win over Partizan Belgrade which sealed Arsenal's progress to the last 16 of the Champions League on Wednesday.
"He has become more efficient and is maturing but he is only 23 and at that age you develop," he said.
"He is an intelligent player and understands that he plays where he can help the team the most. He has all the ingredients to play on the right, left or central and he is happy to play where I play him. Everyone wants to play in the middle but a few have to play on the flanks."
The return to fitness of Robin van Persie further adds to Wenger's attacking options, but things are not so rosy at the back.
"We struggle in defence so we have to score more than we concede," forward Andriy Arshavin said. "It's very frustrating and we're trying to improve. Normally I can't go through our defenders in training but we can't blame just them, we need to improve defensively as a team."
Chelsea have slipped to third after picking up just five points from their last six games and things are not about to get any easier as they follow Sunday's tough trip to Spurs with games against Manchester United and Arsenal.
"I knew we would have a bad period but I didn't think it would last this long," said manager Carlo Ancelotti. "Obviously I'm worried, we have to do better."
