Australia’s championship leader Will Power has crashed out of the season-ending IndyCar race in Fontana, California.

Power was on track to become the first Australian to win the American-based motorsport championship but must now wait for the end of the race before he knows if he’ll win the title.

American Ryan Hunter-Reay must now finish sixth or higher to take out the title.

It is the third year in a row Power has crashed out of the season-ending race when leading the championship.

Holding a 17-point lead going into the race, Power had spent most of the opening 56 laps of the two-mile oval circuit on Hunter-Reay’s tail in the middle of the 26-car pack.

But the 31-year-old spun in an apparent driver error, hitting the wall and wrecking his Penske Racing Chevrolet.

It means Power will be classified with a 25th place finish and pick up 10 points for the weekend, leaving Hunter-Reay needing to gain 28 points to secure the championship.

Speaking after being cleared by the on-track medical centre, a devastated Power isn’t expecting to hold onto his advantage to take the lead.

“It really caught me by surprise, it was the last thing I thought would happen,” the Toowoomba-product told host broadcaster NBC.

“That’s a tough one. It’s depressing to lose a championship that way.

“I just said ‘that’s the championship gone’ … I’m so disappointed for all the guys, just to make a mistake like that, it’s just bad.”