Roger Federer's drive to succeed has landed him seven Wimbledon singles titles and a legion of fans. But when it comes to his children taking up sport, he is determined not to be a pushy parent.
It was an unlikely meeting on the face of it - the Speaker of the House of Commons and the man who is considered by many as the greatest tennis player ever to grace the men's game.
But when John Bercow, formerly Britain's top-ranking junior tennis player, was given the chance to edit Radio 4's Today programme and interview guests of his choosing, Roger Federer was top of his list.
Mr Bercow has watched the Swiss player in action no fewer than 65 times this year and was keen to get to the source of the unwavering ambition that has led him to remain at the pinnacle of his profession.
"I realised very quickly that it's an entirely different thing winning something for the first time and then having to come back the following year and defend it," explains Federer.
"Once I reached a certain level... I looked up to the great other athletes out there [for motivation], like Michael Jordan, Tiger Woods, Valentino Rossi and Michael Schumacher - people who did it so long, so many times and make you wonder 'How did they do that?'.
"Next thing you know," he adds, "it's like you're part of that in a small way, and every year that goes by you get closer to those people. They were definitely a big inspiration for me to keep working hard."
This continued passion for the game has led Federer to a record 302 weeks as world number one, surpassing Pete Sampras's mark of 286.
And after a difficult year in 2013, when he struggled with a back injury, Federer returned in impressive form this season to win more matches - 73 - than any other player on the men's tour.
Once dismissed by many critics as a player in perpetual decline, the 33-year-old remains a serious contender for Grand Slam victory in 2015. Which is just as well, as he admits it would be difficult for him to turn up to a tournament as a sideshow to the main event.
"I definitely am fortunate to always be playing on Centre Court and very often prime time," he says.
"I must say - and this is honest - I don't know if I would still be playing if they would put me on Court 4 every day.
"That would be difficult for me, having played on all these wonderful courts around the world and now playing in front of a fraction of those people - that would be rough."
The will to succeed is clearly a theme of his unrivalled longevity at the top of the game, and Mr Bercow - David Cameron's former doubles partner in the Commons and Lords tennis team - is keen to know whether similar expectations will be pressed on his children.
"I don't know if the kids are ever going to play tennis at a high level like that," says Federer, whose wife Mirka gave birth to their second set of twins this May.
"Honestly, I think it all depends on how things are going to be when we settle in Switzerland, and what sport they are going to take up.
"But I think for any kid it's important for them… to enjoy what they're doing, whatever sport that is."
Federer, however, is keen to make clear the distinction between supportive and pushy parents, especially given the role his father Robert and mother Lynette have played in his success.
"Parental support and advice is very important…to make you understand that it's a privilege to be able to go to tennis lessons and play tennis tournaments. So the least a kid can do is give it their best effort and best attitude," he explains.
"At the same time, the parents also need to give space to the kid and the coaches so they can work and... travel by themselves - the parents don't always need to babysit them through their entire career.
"That's why today when my parents tell me 'You know what, we want to come to every single tournament you play on the tour', I would say 'Yes please, come see me. I don't mind spending every day with you guys for the year.'
"But if they tell me 'We don't want to come see you play because we really don't enjoy it' that's cool too. And that's what I hope every parent can look forward to with their kid," he adds.
"It needs to be both ways and for me that worked very well - I got the space, but I also felt the pressure, the need to perform," he adds.