Heyman says she's hungry to return to the starting No.9 role when Australia challenge the unpredictable Brazil in their Women's World Cup round of 16 clash in Canada on Monday morning (AEST).
The 26 year-old Canberra United forward started in the Matildas' 3-1 loss to United States last week, but was overlooked in favour of Simon for the Group D 2-0 win over African champion Nigeria.
Coach Alen Stajcic's decision paid off, as Simon bagged two goals to help the team progress past the "group of death".
The 23 year-old Sydney FC striker made her mark as a natural goalscorer, combining dangerously with Sam Kerr and Lisa De Vanna who rotated fluently at the flanks.
Heyman, who only got on the field for three minutes of that game, provided some tidy work when was subbed on for Simon in the 72nd minute of this week's 1-1 draw with Sweden.
But she admits it won't be easy reclaiming her spot in an ever-improving Australian team.
"We're all fighting for a spot on the team, and congrats to Kyah for getting her role over me," Heyman said. "I'm trying my hardest to get it back.
"It's not always the easiest position to be in, but I'm just grateful I'm part of the team and I hope that for this game I can show my stuff."
Teammate Tameka Butt is facing the same issue in the midfield, where Katrina Gorry, Emily van Egmond and the hard-working Elise Kellond-Knight hold the fort.
Butt got her first tournament game time against Nigeria but was only granted a few short minutes to prove her worth against Sweden.
She admitted the limited opportunities can be frustrating.
"It's hard to do that considering a lot of our days after a game are recovery," she said.
"We don't have a lot of training sessions where you can prove yourself, and we tend to do a lot of tactical work.
"But (when) you're a footballer, everyone's competitive in a team."
It's all part of the grand plan for Stajcic, who's been building a culture of internal competitiveness to grow his players' depth and flexibility.
"If you're in form you're going to get picked," Stajcic said after the Sweden match.
"If you get a spot in the team and you play well, you keep that spot.
"No one has a mortgage on any position in the team.
"There's players on the bench who are potential starters in this team and have been for a long time.
"But when they get their chance they're going to have to grab it with both arms."
WATCH #BRA v @TheMatildas in the #FIFAWWC LIVE on SBS this Monday. More news here http://t.co/iWTd8X14Ow #SBSTWG http://t.co/M9Or3I77zm — SBS - The World Game (@TheWorldGame) June 19, 2015
