Jason Day made a spectacular return to the Australian Open on Thursday, finishing the first round three shots off the lead as defending champion Jordan Spieth struggled in tricky conditions.

Day, playing his national open for the first time in four years, made the most of his early morning tee time, rolling in eight birdies in perfect sunshine for a superb round of five-under-par 66.

The former world number one finished the opening day tied for third place with Nick Cullen and Alex Edge, as Cameron Davis set the pace with a blistering round of 63 to lead by two strokes from Taylor Macdonald at The Australian Golf Club.

Spieth, playing in the afternoon when the wind had picked up, battled his way to an up-and-down round of one-under-par 70 to end the day seven shots off the pace on a heavily congested leaderboard.

Unable to build any momentum after making bogey at his first two holes, the American dropped three more shots but brightened up his card with six birdies, including a 20-foot putt at the final hole that fell into the cup.

"I take a lot of pride in bounce-back stats -- after a bad hole, coming back and making a birdie. I did that, but then I was on the other end of it," Spieth said.

"I bogeyed just about every hole (after) I made a birdie. Fortunately, we finished on 18 with a birdie. I can't bogey the 19th hole."

Playing the back nine first, Day dropped a shot at the par-three 15th hole when he drove into the trees, then double-bogeyed the eighth hole, his second last.

But he was otherwise pleased with his performance as he chases his first Australian Open title in a rare outing in his homeland.

- 'Good start to the week' -

"I made a couple of mistakes out there with some swings, but made, I think, eight birdies, which was nice and finished at five-under, which is a good start to the week," Day said.

"I think it would have been a little bit disappointing if I came out this morning and shot an even-par round. I think it's definitely out there to shoot a deep one.

"That's kind of the thing, you almost need to come out and capitalise when there's no wind, because it's very warm in the morning, the ball's starting to go a lot further in the mornings and there's no wind."

Davis, also playing in the morning, birdied six of his first seven holes before the wind gusts put a halt to his phenomenal start and he eventually signed for a 63, enough to grab a two-stroke lead over Macdonald, ranked 1,809th in the world.

Davis, who turned professional after winning the 2015 Australian Amateur title, and then helping Australia win the Eisenhower Trophy in 2016, could hardly contain his excitement after chipping in for birdie at the seventh to get to six-under.

The 22-year-old made his only bogey of the day at the ninth but regained his composure and covered the back nine in three-under to claim the first day lead.

"To be able to play the back nine without any bogeys, just keep on making a couple of birdies, I felt like that kind of shows that I was able to not get too far ahead of myself, which has definitely happened in the past," he said.

"That's one of the things I feel like is improving for me."

New Zealand's Brad Shilton made the best start of any player on the day, making a hole-in-one on his second hole to win himself a Au$16,000 wrist watch. But his luck quickly ran out as he made four bogeys and three double bogeys in a round of 78.

Source: AFP