Gibson fired a six-under-par 66 at Coco Beach Golf Course on Thursday to be two shots behind leader Kyle Stanley.

The 34-year-old Victorian made eight birdies with two bogeys to join Americans Peter Uihlein, Josh Teater and Chris Couch, Argentina's 2015 runner-up Emiliano Grillo and Sweden's Henrik Norlander in a six-way tie for second.

Gibson put his bogey on the first behind him to shoot birdies on the second, sixth and seventh holes to be two under on the front nine.

He then birdied 12, 13 and 14 before a bogey on 16 stymied his progress. However, he finished strong with further birdies on 17 and the last.

Cameron Davis is the next best Australian, his three-under 69 securing him a tie for 20th.

John Senden and Cameron Percy are a further shot back with Robert Allenby even par.

The 32-year-old Stanley, who is looking for his third PGA Tour title, recorded a flawless back nine which included four birdies before making five further gains on the front nine.

The $US3 million ($A4.5 million) Puerto Rico Open is up for grabs with the world's leading players all locked in battle at the World Golf Championships in Mexico.

Australian Associated Press