Roger Federer has stressed that he does not want to slip into a "bubble" following his return to the top of the ATP rankings.

The 36-year-old has already taken part in two tournaments this season – Australian Open and the Rotterdam Open. He defeated Marin Cilic in the first Grand Slam final in Melbourne, which was followed by a victory over Grigor Dimitrov in Holland.

Federer also eclipsed 10-time French Open winner Rafael Nadal to become the new world No.1 after he made it to the semi-final of the 2018 Rotterdam Open. By achieving this feat, he became the oldest player to reach the top of the ATP rankings, surpassing Andre Agassi.

The 20-time Grand Slam winner is aware that he has to be at the top of his game in order to retain the world No.1 tag. He is also wary of the fact that his moves will be closely followed and stressed he does not want to discuss his "magic formula, if there is any."

"As you're riding the wave and have the momentum, you want to try to maintain that as long as possible so you sometimes do tend to go into a bit of a bubble. I try not to ever really go there," Federer explained was quoted as saying by ATP's official website.

"I think when you're at the top, everybody is watching everything you do extra carefully so you maybe go into a shell to some extent because you don't want people to know your magic formula, if there is any."

Roger Federer
Roger Federer says everybody is watching everything you do extra carefully when you are on topGetty Images

The Swiss tennis ace will be in action at the 2018 Indian Wells, which already kick-started on March 8. He will take on Federico Delbonis in the first round of the first ATP World Tour Masters 1000 of the calendar year.

Federer had won the tournament in 2017 and holds the record with Novak Djokovic for the most number of wins in the tournament. The tennis legend explained that he still has the desire to be successful as he targets his sixth Indian Wells title in 2018.

"You always have [something to prove]. As much as I'd like to tell you, 'Yeah, it doesn't matter how I play here', I didn't come here to lose in the first round [6-2, 6-2]," he said.

"You care about that moment, about the fans, and how they portray you. You care for the result; you care for so many things. As little pressure as there seems to be, there is always pressure on the top guys. You're always at the center of attention and expectations are there."

"I'm definitely in a good place. I feel like I have less to prove today than in the past, but that doesn't mean that I don't want it badly. I need to have that drive to be successful."