The 22-year-old is looking forward to the big game after the comprehensive victory in Europe, while praising Wayne Rooney and Robin van Persie for combining with "great effect"
David Moyes led the club to the 4-2 victory in his first Champions League game in charge, but the tough fixtures keep coming with a trip to local rivals Manchester City on Sunday.
The Spanish keeper is relishing the clash as the reigning champions get set for their third high-profile Premier League game in a month, following a goalless draw against Chelsea and defeat at Liverpool.
"The victory (against Leverkusen) has boosted our confidence for Sunday," De Gea told the club's official website.
"It was important to kick off with a win; we made a good start and got the three points, which gives us peace of mind.
"We've since had a few days to prepare for City and we're looking forward to the match."
The 22-year-old was also full of praise for attacking duo Robin van Persie and Wayne Rooney, with the latter celebrating hitting an impressive milestone of 200 goals for the club on Tuesday.
"Not only did he (Rooney) score goals, he played some great football, worked hard, brought dynamism to the team and played a really great game," he added.
"It’s good for us that he and Robin score goals. It is important; they are key players and this year they will combine to great effect."