Adam Scott finished as leading Australian at five over for the championship, 11 shots adrift of Spanish champion Jon Rahm.

Scott birdied the last hole but five bogies for the second straight day once again stalled the former World No.1's challenge after he had opened the tournament with a promising one-under 70 to be right in the mix.

Scott shared 37th spot, one stroke ahead of European Tour veteran Wade Ormsby, who closed with an even-par 71 to tie for 40th in his first major since missing the 2017 US Open cut.

With gum trees lining familiar fairways on the Pacific Ocean, Torrey Pines had been a happy hunting ground for Australians.

Leishman shot six-over 77 on Sunday at Torrey Pines. PHOTO: Sean M. Haffey/Getty Images.

Marc Leishman won the Farmers Insurance Open there last year and boasts two other runner-up finishes on the San Diego layout.

But Leishman never got going on Sunday, amassing six bogies in a birdie-free round of 77 to complete his Open at 12 over and sharing 64th spot.

He was one shot better than Matt Jones, whose final-round 75 left the two-time Australian Open champion in 65th position.

With former World No.1 Jason Day failing to qualify and Cameron Smith missing the cut, the tournament marked consecutive majors in which none of Australia's PGA Tour stars managed to place in the top 30.

Day was best of the big guns at last month's US PGA Championship, typing for 44th at Kiawah Island.

They'll have one last crack at major championship in 2021 at next month's Open Championship at Royal St George's, the scene of Greg Norman's second Open triumph in 1993.

- Darren Walton, Australian Associated Press