At 10 under, Thomas commands a three-stroke lead over world No. 1 Scottie Scheffler and Arnold Palmer Invitational winner Russell Henley. Battling a bad back, former U.S. Open champion Wyndham Clark impressed in the early afternoon hours with a 65 of his own to stand four adrift.

Justin Thomas equals course record to take three-shot lead at RBC Heritage - Thomas carded 11 birdies in his opening round 61 at Hilton Head.

In Thursday's first round of the RBC Heritage, Thomas fired a 10-under-par 61 at Harbour Town Golf Links, which ties the lowest professional score at the course, which has hosted the PGA Tour since 1969.