Roger Federer is hopeful continued careful planning can ensure he adds to his record haul of 20 grand slam men's singles titles.

Already the most successful male player in history, Federer added yet another major trophy to his collection on Sunday when he retained the Australian Open courtesy of a five-set victory over Marin Cilic in Melbourne.

Federer now has four more slams than his great rival Rafael Nadal, but the 36-year-old says he has "no idea" how much longer he can thrive at the highest level.

Having now won back-to-back Australian Opens either side of a Wimbledon triumph in 2017, Federer believes limiting his schedule will be key.

The Swiss, who sat out the entire clay-court season last year, said: "I've won three slams now in 12 months. I can't believe it myself.

"I just got to keep a good schedule, stay hungry, then maybe good things can happen. Then I don't think age is an issue, per se. It's just a number.

"But I need to be very careful in my planning, really decide beforehand what are my goals, what are my priorities. I think that's what's going to dictate how successful I will be."

Federer was eager to highlight the role of his wife, Mirka, in his sustained success.

"Without her support, I wouldn't be playing tennis no more [sic] since many years," he added.

"But we had a very open conversation, if she was happy to do this or not, years ago. I'm happy that she's super supportive and she's willing to take on a massive workload with the kiddies [two sets of twins].

"This life wouldn't work if she said no. Many puzzles need to fit together for me to be able to sit here tonight."