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."