Mats Wilander believes Roger Federer's change to a bigger racket has helped him play the best tennis of his career.

The 35-year-old won his eight Wimbledon title after a dominant straight set 6-3, 6-1, 6-4 victory over an injured Marin Cilic on Sunday (16 July).

Read more Roger Federer expects to return next year and defend Wimbledon title

It marks a huge career resurgence for Federer who now has five titles in the calendar year since returning from a six-month injury layoff.

However, the Swiss ace endured arguably the worst year of his professional career in 2013, winning just one title in the Halle Open.

Federer opted for a bigger racket the following year, going from 90" to 97" which has considerably improved his backhand shots, as he admitted earlier this year during Indian Wells.

"I think the backhand has gotten better because I have been able to put in so many hours onto the racket now," Federer said in March, as quoted on Tennis.com. "And since this year, I feel super comfortable with the racket, and I think I have gained confidence stepping into it."

Wilander, a former world number one, spoke about the impact of the bigger racket, wondering why Federer did not switch to it even earlier.

"I ask myself why he didn't switch to the bigger racket before," Wilander stated, as quoted on Tennis World USA. "It made him hit backhand earlier. Roger was probably focused on smaller rackets for a long time. If he wasn't tested, he would not have had that strength and so he would have called it a career. He is serving better than the past as well."

"He understood that he had to focus more on this shot [backhand] in order to compete with Rafael Nadal or Novak Djokovic from the baseline. Looking at his age, Roger is showing that in tennis the body is not the most important thing."

Despite extended breaks being a factor for Federer as well, Wilander also stated the importance of attitude and how it has helped the world number three overcome his age.

"It's all about mentality and passion," Wilander added. "If you are willing and physically you are doing well, being 25 or 35 is the same thing."

"Now Federer is clearly a better player than he was ten years ago when he dominated. Probably his third round match against Tomas Berdych at the Australian Open was the best match of his career."