Holden Motorsport's technical manager Peter Harker is recovering in hospital after suffering a heart attack at the Castrol Townsville 500.
The 57-year-old was transferred to Townsville Hospital by trackside medical staff after the attack occurred this morning.
Harker's exit from the circuit via ambulance caused a short delay to the start of the opening V8 Supercars practice session.
A Holden Motorsport spokesman told Speedcafe.com that Harker is now recovering after surgeons inserted stents in blocked arteries.
Working alongside Holden Motorsport manager Simon McNamara, Harker has headed up the company's technical projects for more than a decade.
Trackside regular McNamara is absent from Townsville this weekend due to holidays.