Australia's Adrian 'Ace' Buchan has beaten 11-time world champion Kelly Slater in the final of the Billabong Pro surfing event at Teahupo'o in Tahiti.

Buchan's giant-killing run included the scalps of countryman Mick Fanning and South Africa's Jordy Smith before he beat Slater 18.94 points to 17.9 points in the final.

It is Buchan's second tour victory.

In his first, in France in 2008, he also beat Slater in the decider.

Australia's reigning world champion Joel Parkinson was beaten by Slater in the fifth round in a severe dent to his chances of retaining his world crown this year.

Slater will become the new rankings leader, ahead of Fanning, while Buchan of Avoca Beach on the New South Wales Central Coast has broken into the top 10 after the sixth of 10 events in 2013.

Buchan set the standard in the final scoring an early 9.67 out of 10 tube ride before Slater responded with a 9.27.

Buchan backed up his first score with a 9.27 and was relieved when Slater's final wave score (8.80) fell short of what was needed to take the heat.

"I thought he snatched it from me at the end," Buchan said after his win.

"I can't believe it. It hasn't sunk in yet. What an incredible day."

"I thought that I stepped it up today and I had to, to beat the likes of Kelly and Jon Jon (Florence)."

Buchan beat Hawaiian rising star Florence in the quarter-finals before eliminating Australian two-time world champion Mick Fanning in the semi-finals.

An emotional Buchan dedicated the win to the Tahitian family he has stayed with while competing at Teahupo'o for the past eight years.

"This trophy is for them and it'll stay at their house forever."

AAP/ABC