The pair clash at Old Trafford when Jose Mourinho's men will look to maintain their superb start to the season.
The Blues are five points clear at the top of the table following an unbeaten start that has seen them drop just two points.
Mourinho's men are strong favourites to brush aside United and then go on to win another Premier League title.
It promises to continue new United boss Louis Van Gaal's baptism of fire as he continues to find his feet in English football.
United are languishing in sixth place in the table and trail the Blues by 10 points already.
Van Gaal's men have won just three of their opening eight league games and De Gea knows the visit of the Blues will be the acid test of United's development.
The Spanish goalkeeper said is relishing the challenge but knows it will be a tough afternoon for the former champions.
He said: "They (the Blues) have started the Premier League season unbelievable.
"They have won nearly all their matches. They have a great team and great new players. They are a difficult team to beat.
"They are special games against Chelsea and I like them a lot. Everyone wants to play in these games, the top games.
"Of course the other games against any team in England are difficult and you have to focus on every game, but these games are a little bit special."
De Gea, meanwhile, believes he has a new rival for the tag of 'best keeper in the top flight' in the shape of Blues ace Thibaut Courtois.
The Belgium stopper has replaced Petr Cech as Mourinho's new No.1 at Stamford Bridge and De Gea added:
"I saw him at Atletico Madrid. He played very well. He's a great goalie.
"He's young, he's big, he's a good shot stopper and he's good with crosses. He is one of the best."
