Former world number one Roger Federer has told BBC Sport he wants to win at least 20 Grand Slam titles before he retires from playing.
The 16-time Grand Slam winner told BBC Radio 5 live he thinks it is "do-able".
"I believe that having won three Grand Slams per season three times, and two per year a couple of times, it's something do-able for me," he said.
"I only play 16-20 tournaments per year, so I'm not over-playing, and that keeps the fire burning."
This year's Wimbledon saw Federer fail to reach the final for the first time since 2002, as he lost in the quarter-final to eventual runner-up Thomas Berdych.
And although the 29-year-old admitted he is increasingly feel the stresses and strains of playing, speaking in the build-up to the US Open he said he still had plenty of motivation for carry on playing for a while yet - in tournaments of all kind.
"At times I was one or two sets away from winning the calendar-year Grand Slam so obviously I feel that I have a great potential in Grand Slam play. But then again Grand Slams are not everything," he said.
"I'm giving 100% for each and every tournament that I play because I don't play a ton of tournaments.
"Tournaments like Toronto this week and Cincinnati next week are important to me, too. The motivation is huge for the next few years and obviously if I can win Grand Slams that's fantastic, but they are not the only motivation over the next few years."
Federer admitted he did not watch this year's Wimbledon final, as there was not a television where he was on holiday with his family, but said he did not feel any great sense of loss at missing out on the final.
"When you have disappointing losses or a tournament ends early for you, you move on with your life. You don't think 'shouldn't I be at Wimbledon in the finals?', you kind of enjoy the moment with your family, with your friends, just being away from it all," he said.
Federer looked out of sorts at Wimbledon this summer
"That's what I do very well. I switch off very quickly, I don't think of tennis that much when I'm away from the courts, even though subconsciously I have to because I'm a professional and I want to do really well in the long run in tennis.
"So, that was kind of nice [to be away]. Then again, I started to miss tennis as well so I was happy to get back on the practice courts, too."
After his Wimbledon defeat by Berdych, Federer complained of back and leg "issues".
But rejuvenated by a holiday and refreshed by two weeks working with new coach Paul Annacone, he said he felt "perfect" ahead of his return to action in Toronto this week, as he starts his build up to trying to win a sixth US Open title.
And he said with age comes a better understanding of how to get the best out of his body.
"Being a teenager is different to being 23, and being 23 is very different to say being 28. Today, I know my body better than ever," he stated.
"Some things take a little bit longer [to recover from] with age but I can prevent more problems by doing a lot more stretching, physical work, practice, massages. I'm doing everything much more professionally today than I ever have before.
"That's the advantage [of being older], but then of course there's no denying that I've played almost a thousand matches in my life and that obviously has a big wear and tear on your body, too, so you have to be a little bit more careful."
A full version of this interview can be heard on BBC Five Live this evening at 1930 BST
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