Marin Cilic believes that Roger Federer becoming the oldest player ever to top the ATP rankings is an inspiration for all. His achievement proves that with proper preparation and management one can still perform to his best at 36.

Federer beat Cilic in the final of the Australian Open last month in an engrossing five-set contest. The Swiss ace held his nerve to win his 20th Grand Slam title. In the process, he became only the fourth player after Margaret Court, Serena Williams and Steffi Graf to win 20 or more major singles titles.

Federer followed that up by winning the Rotterdam Open, picking up his 97th title in his illustrious career. When he reached the semi-finals of the event, he became the oldest player to top the ATP rankings.

He broke Andre Agassi's long standing record – the American was 33 when he reached the summit in 2003. Federer took the title by beating Grigor Dimitrov in the final in straight sets.

Cilic lost two Grand Slam finals in the past six months to Federer - Wimbledon and the Australian Open. The Croat says Federer deserves to be No 1, because he continues to show that you can improve when you get older.

"It's an amazing achievement for him," Cilic said, as quoted by the Express. "He put himself in the position to be number one again. For tennis it's great. He is an example that you can still improve at the age that he is."

Meanwhile, Federer has revealed that he expected a more difficult time from Dimitrov in the final of the Rotterdam Open, which the Bulgarian lost 6-2 6-2.

"No, of course not [I did not expect it to be this easy]," Federer said. "I was expecting it to be tough and of course, be in trouble to be quite honest because Grigor's a great player, a great athlete, he's been playing super well in recent months so I thought this was not going to be the result.

"I think he struggled a little bit at some point in that first set but honestly, I never looked back, I played great and felt the best by far this week.

"I just think I was able to execute the tennis I wanted to and Grigor couldn't hold against it because he was maybe feeling a little dizzy and stuff but I was able to take advantage of that and get the title so I'm very, very happy."

Marin Cilic and Roger Federer
Cilic has lost two Grand Slam finals in the last six months to Federer Getty Images