Tough, resilient Simon always destined for superstardom
The duo was together at the New South Wales Institute of Sport, with Simon nursing a broken leg.
A ruptured anterior cruciate ligament in late 2013 put Simon's Women's World Cup in doubt, mostly due to uncertainty about her condition on return.
Yet, on Saturday morning (AEST), she was Australia's hero – netting a brace in an important 2-0 win over Nigeria.
Stajcic never doubted the 23-year-old.
"I've known Kyah since she was 14 or 15," he said.
"I brought her into my program while at the New South Wales Institute of Sport and she had a broken leg.
"She had that broken leg. She was out for nine months.
"To see a kid with that resilience and toughness, I knew she was a world-class player back then, just to come back from that.
"She could barely jog and run when she came back and she's had – this is her third major injury now – and just [has] the resilience and toughness to come back."
In a warning to the Matildas' upcoming opponents – Sweden on Wednesday (AEST) – Stajcic says Simon will get better.
"We've really taken it easy with her over the last three or four months and just built her up slowly because we knew we wanted her to be at her peak for the World Cup," he said.
"And the best part is I still think she's got more in the tank.
"I thought she was good today, I think she can be even better.
"I think she's a potentially world-class player.
"She had a couple of really good moments today, but if she stays healthy and fit she's going to be a threat to anyone at this World Cup."