The two young drivers were slated to compete in Perth next month, but their third wildcard starts of 2021 will now take place at Phillip Island.
The weekend will mark another key opportunity for Kostecki and Randle to impress, with Randle already confirmed in a Tickford Racing full-time drive for 2022.
Kostecki impressed at The Bend and Hidden Valley
Both drivers have already scored top 10 results, with Kostecki’s sixth in Darwin the best finish across both drivers.
Another strong performance and Kostecki could throw his hat in the ring for a full-time 2022 drive, possibly alongside Chaz Mostert at Walkinshaw Andretti United.
However, Kostecki cast his gaze to build on his solid Tailem Bend and Darwin outings.
"It’s awesome to have Phillip Island confirmed as my third wildcard for 2021 with WAU," the 23-year-old said.
Kostecki battles at The Bend
"It’s a real shame we can’t get to Perth this year, I was really looking forward to racing at my home event, but I’m still really excited to head to Phillip Island.
"It’s one of the most iconic circuits in the world, so I can’t wait to get there and get behind the wheel of the Mobil 1 No. 27, and build on what we’ve achieved and learnt across the previous two rounds.”
Neither Kostecki or Randle has made a main game start at Phillip Island.
Kostecki scored finishes of 12th, eighth and eighth in the Super2 event in 2016, and recorded two more top 10s in 2017.
The 2021 season will resume at Winton across October 2-3.