On one pitch the women's team was being put through its paces. His initial intent had not been to watch the girls play, but he was drawn in by a 13-year-old who could glide away in the smallest of spaces. She was quick, athletic and blessed with "raw talent." She was, he says, exceptional.
Though her rise to the higher echelons of women's football has come as no surprise to her coach Despotovski, Kerr once described herself as being "total crap" in her first season of playing the game.
To understand Kerr's description of her younger self it is to delve a little deeper into how the finest player Australia has produced came to play the beautiful game.
Kerr too was also a talented AFL player. At home she would pluck imaginary balls out of the air and practice with her three brothers. She was the lone girl who would star in boys' teams until, aged 12, she reached the end of the road.
The differences between the sexes had become too pronounced and so Kerr switched to football, a sport which was alien to the AFL community she had been brought up in.
Had there been a pathway for girls in AFL, Kerr admitted her life would have taken a different turn. "I would have missed out on all of this," she told reporters on the eve of the Women's World Cup. "The rug was ripped out underneath me," is how she described being forced to stop playing the childhood sport in which she shone.
For a sport she did not immediately fall in love with, Kerr's progress was startling. Aged 15 and 150 days, she made her international debut, having already become the youngest scorer in the W-League -- Australia's top division -- and voted players' player of the year.
Though she has previously said her intention was to retire aged 21, Kerr is still playing and for that Australia is grateful.
She splits her time between Australia and the US playing for the Chicago Red Stars in the American National Women's Soccer League (NWSL) and Perth Glory in the W-League and is the all-time leading scorer in both leagues. Feats achieved despite suffering three major injuries.
How did Kerr become so good so quickly after an inauspicious first season? Work ethic, says Despotovski, who described the 25-year-old as an easy player to coach because of the Australian's desire to "improve all the time."
But with national hero status comes responsibility, not that the easy-going Kerr, whom Despotovski confirms is a joker, is the sort to let the hopes of a nation weigh heavy on her shoulders.
"She's a very bubbly person, nothing bothers her," he said. "She comes to a training session and takes the young girls that we have in the squad under her wing and tries to introduce the work ethic she has.
"Even at 25, she's very mature and trying to pass all of that to the younger generation."
In January Alen Stajcic, the coach which guided the Matildas to the quarterfinals of the 2015 World Cup and to a high of fourth in the world rankings, was surprisingly sacked and replaced by Ante Milicic.
One of Milicic's first decisions as the Matildas' new boss was to make his star player the captain. It was an appointment Despotovski regarded as shrewd because it is not only speed and ruthlessness in front of goal which marks Kerr as a great but leadership too.
"She doesn't lead by words or anything like that, she leads by action on the field," said Despotovski of a player who scored in that opening game against Italy.
Kerr has admitted that the team's form over the last two years has brought with it its own pressure, both negative and positive. With unprecedented success comes expectation.
"The biggest change for myself and my team is the publicity around the team," Kerr, now in her 10th year as an international, told CNN Sport before the tournament.
"The interest in the team from the last World Cup to now is day and night. Obviously with the good comes the bad, but I think it's been mostly positive.
"Everyone's got behind us and loved the way we played but with that comes that pressure, the pressure to have to perform. The year everyone got behind us we had so many good results and that's what people expect of us. We like that, we like that we have high expectations, but it's new for everyone to have this type of pressure and to not disappoint people."
Though Kerr's personality allows her to take most things in her stride, her maturity and experience has also helped her adapt to the mental pressures that come with being a professional sportswoman.
She admitted she has changed the way she approaches a game. In her younger days she used to play a forthcoming game over and over in her head, but it was an approach which eventually played with her mind. These days she tries not to think too much.
"I like to keep it calm on game day. I'm pretty chilled so it's just finding the balance between being focused and also feeling relaxed before the game and supporting my teammates," she said.
A nation awaits to see what their fearless million dollar player can do.