Law, now a tennis commentator with a podcast series called The Tennis Podcast, has seen Federer grow from a boy into a man at close quarters. He first met the tennis prodigy the day before Federer's professional debut as a 16-year-old at an event in Switzerland and has continued to watch in awe - like most of us - at his evolution into perhaps the sport's greatest ever male player.
Law remembers the early days, when Federer made Kyrgios and Tomic look like saints.
"The number of times we would go to tournaments and he would throw in a substandard performance where he'd mentally break down or he'd get emotional and throw his racquets - he was a baby. Honestly, he was a crybaby on the court," Law says in a Tennis Podcast special.
"He was just immature and it took him a while (to grow up)."
Former Swiss star Marc Rossett backs this assertion up when audio of him is played in the same podcast.
"I remember the first time I practised with him ... he was the new talented guy in Switzerland but he was so lazy," Rossett said.
"Usually when you practise on the tour as a young guy you are a little bit stressed, you want to play good, you're very nervous. The guy came on the court like he didn't care at all. I was like, 'Wow.'
"The first time I played him was at a tour event in Marseilles and I won 7-6 in the third (set) and I remember it was his first final ever and he was crying at the ceremony and I was like, 'Come on, don't cry.'"
But it wasn't just on the court where Federer's emotions came out. Law reveals moments the public didn't see with former coach Peter Lundgren and inside the locker room that add an extra layer to his early wild child image.
"It was growing pains. He was a teenager, he was silly, he was into music, he was into stupid computer games," Law says.
"Anything loud (was the type of music Federer listened to). I know Peter Lundgren used to take him out in a hire car in Miami and they'd stick on ACDC and he'd sing it and shout it at the top of his lungs.
"People don't realise what an exuberant character Roger Federer is, how loud he likes to be.
"In the locker room and the showers he'd be screaming at the top of his voice doing impersonations of other players and characters that he might have seen in the World Wrestling Federation and things like that just because he had so much energy. I don't think I'd ever seen anybody on the circuit with this much energy."
Can you imagine pairing those anecdotes with the sedate, measured, calm Federer we're privileged enough to witness today?
A lot has happened since Federer cried after losing his first tour final. He's won 19 grand slams, for one. That two of those crowns have come in 2017 - at the Australian Open and Wimbledon - despite a lengthy injury lay-off last year only add hype to the Federer legend.
But how do you go from a brash, belligerent teen to a 19-time major winner? In Federer's case, it's not all because he spent countless hours working on the most famous one-handed backhand in the game or on developing soft hands at the net.
Law pinpoints three moments that have shaped Federer as a player and as a man. One such moment he was powerless to control.
Peter Carter coached Federer between the ages of nine and 18, and the current world No. 3 credits the Australian with having "the biggest impact on me in terms of my technique". But Carter hasn't been able to see all the fruits of his labour, dying in a car accident while on safari in 2002 a week before Federer's 21st birthday.
Law says Carter is the primary reason Federer didn't slide down a slippery slope as a young, angry talent, and believes Carter's death shocked him into maturity.
"Peter Carter just kept him on the straight and narrow really and stopped him getting into any trouble," Law says. "Federer was devastated.
"That made Federer grow up incredibly quickly because I don't think he'd ever had to think about mortality before.
"It stopped him in his tracks and it caused him problems for a long time in terms of dealing with it, dealing with the grief. This is someone he knew well, who he saw everyday, who he travelled everywhere with.
"It hit Federer incredibly hard and I think that - and this is a feature of Federer as a boy becoming a man - is that at every stage of his life, whatever has happened, he's digested what has happened and he's learnt from it. He's moved onwards.
"He will never forget the lessons that man (Carter) taught him and it's a terrible shame he wasn't alive to see everything Federer's gone on to win."
Many people point to Federer's win over tennis great Pete Sampras in the round of 16 at Wimbledon in 2001 as the moment that sparked his career's upward trajectory. Federer was just 19-years-old, 10 years Sampras's junior, coming up against the reigning champion at the All England Club.
Federer won that contest in five sets 7-6 5-7 6-4 6-7 7-5. It was a turning point in the Swiss maestro's career, but Law says there were even more poignant moments than that watershed victory.
Two years later at the same venue, Federer won his first grand slam title. In the semi-finals he played big-serving American Andy Roddick who, at basically the same age as the Fed Express, was making his mark on the world stage.
Federer breezed through the clash of the two great generational talents 7-6 6-3 6-3. He then overran Aussie Mark Philippoussis in the final 7-6 6-2 7-6. A star that had been simmering finally burst to light.
"Federer and Roddick were coming up at the same time - I was always arguing with my American counterparts about who was going to have the better career out of Roddick and Federer," Law says.
"Federer won that match and that's when the world discovered this guy's talent. He soaked up the serve of Roddick, the game of Roddick and just his sheer skill won that match for him. And then he beat Mark Philippoussis in the final.
"That was the moment that the weight lifted off him and you could see that. This moment of, 'I've no longer got everyone asking me if I'm going to be the next big thing or the next champion, I at least am a champion.' You could see that."
Then came a shock change. Federer split with Swedish mentor Lundgren just three weeks after defeating Andre Agassi to win the season-ending Masters Cup (now the ATP Finals) in 2003, a tournament played between the top eight ranked players at the end of the year.
It was a surprise given Federer had just come off what was then the most successful season of his young career. At 22, he was ready to go from good to great.
"At the Masters Cup he was extraordinary. He beat Andre Agassi in the final, then he split with Peter Lundgren and it was a real shock to all of us in tennis," Law says.
"I feel that was the separation of Roger Federer from boy to man - he no longer needed a mate on tour.
"He (Lundgren) was a mate of his. He would sit in a car with him, turn on the music, let him scream his head off on the highways of Miami, play silly games, get all that out of his system.
"Suddenly Roger Federer started to become a man. He didn't need that looking after anymore."
Though wife Mirka might disagree, from the tennis world's point of view, he hasn't needed looking after since.
