Defending champion Justin Thomas launched the defence of his CIMB Classic title in Malaysia with nine birdies en route to an eight-under-par 64 on Thursday.

The American was joined at the top of the first-round leaderboard by compatriots Derek Fathauer and Keegan Bradley, with England's Paul Casey one shot back.

Thomas, 23, who clinched his maiden PGA Tour title here in 2015 after a tournament record 26-under-par 262, kept his cool despite hot and humid conditions to card just a single bogey at the TPC Kuala Lumpur course.

"It was a good day... it was solid. If there's such a thing as an easy eight-under, it was. I wedged it great," he said.

Anirban Lahiri of India was in range with a 66 while recent Ryder Cup victor Patrick Reed of the USA, the world number seven, was four shots back with a 68.

Adam Scott, the highest-ranked player in the field at number six, was left to rue three bogeys that left him six shots back.

Scott, who finished in the top 10 in his last four tournaments, vowed to come back more aggressive.

"I hit a few bad shots in the round and made some bogeys unfortunately. It's really good scoring conditions, so that was costly," said Scott. 

"Yeah, I think you need to play aggressive. I really need a low round tomorrow and get up near double digits under par, and try and get back in this thing."

Ryan Moore, who is bidding to win the CIMB Classic for a third time, stumbled out of the gates to a one-under 71.

The 33-year-old, another member of the winning USA Ryder Cup team, won in 2013 and 2014.

The $7 million tournament is jointly sanctioned by the Asian Tour and the PGA Tour and offers US$1.26 million to the winner. 

It is the second event of the PGA Tour's 2017 schedule, and offers 500 points toward the FedEX Cup championship, as well as an invite to the winners-only 2017 Tournament of Champions.

Source: AFP