Herbert fired a five-under par 67 in qualifying at Carnarvon Golf Club in western Sydney on Monday to grab one of the final eight spots in the field for the Australian Open at The Australian, starting Thursday.

The Bendigo 18-year-old needed a birdie on the 18th hole to avoid a play-off and he calmly delivered to secure his place in the field alongside Rory McIlroy and Adam Scott.

"Mentally, I'm pretty drained, but I'm really happy right now,'' an elated Herbert said after qualifying.

"Physically, I'm okay, my swing held up really well today."

Golf Australia had promised the amateur star automatic entry to the Australian Open if he finished in the top 10 at the Australian Masters.

A double bogey on the 18th in Sunday's final round saw Herbert slip from a tie for fifth to a tie for 11th and forced him into qualifying for the Open.

Unable to get a flight from Melbourne to Sydney on Sunday night, Herbert and his parents, Lyndon and Meredith, made the decision to drive overnight to ensure he made his 9.38am tee time.

"I slept better than I expected to, but sleeping in the back of the car isn't great,'' Herbert said.

"It gave me enough rest for today and I hit enough good shots to give myself enough chances.

"I made birdies on three of my last six holes to get in, so that was nice."

It will be Herbert's first Australian Open appearance.

"It's very exciting,'' he said.

"I need to get some rest today and then get back into it tomorrow."

For Lucas' parents the long drive was worth it.

"It's been a tiring 24 hours, but everything has worked out fine,'' Lyndon Herbert said on Monday.

"Lucas played well today and earned his spot in the Open field. It's a great learning experience for him.

"In golf he's at the bottom of the learning curve and he has a long way to go."

Lyndon and Meredith shared the driving duties to Sydney so Lucas could sleep in the back seat of the car.

"I drove to Holbrook then Meredith did a stint to Goulburn,'' Lyndon said.

"I got a couple of hours of sleep in. I'm a bit tired now, but it's been worth it."

Lyndon caddied for his son at Carnarvon.

"Coming to the 17th hole we knew he needed to birdie one of the last two holes to qualify outright,'' Lyndon said.

"On 17 he just missed a birdie putt and on the 18th tee we had a chat about what was the best way to go about it.

"Lucas was confident he could make a birdie and he played the hole well.

"It was a relief that he didn't have to go into a play-off."

Herbert will be joined by Bendigo professionals Andrew Martin and Kris Mueck in the field at The Australian.

Bendigo-born pro Rhien Gibson, who equalled Herbert's course record 65 at Metropolitan on Sunday, will also play the tournament.