PGA Tour rookie Davis Riley shot a blazing 62 on Saturday to vault to the top of the leaderboard at the Valspar Championship in Florida.

Davis sits at 18 under par and holds a two-shot lead over Matthew NeSmith, who shot 69 one day after matching the Valspar single-round mark record with a 61 on Friday.

Davis carded nine birdies en route to a bogey-free round at the Innisbrook Resort's Copperhead Course to set a new 54-hole scoring record for the event.

Justin Thomas, on the back of a third consecutive 66, and defending champion Sam Burns (67) sit three shots back at 15 under.

Ireland's Shane Lowry carded a second consecutive 68 and is 10 shots off the lead.

Riley had never held a tournament lead after any round until Saturday, and his round was three stokes better than his previous career best of 65 at the Sony Open in January.

"I struggled a little bit with my approach play. I wasn't as clean as I would like to the first two days, but thankfully the putter was there," Riley said afterward.

"And that's what I've been telling myself is just give myself a look. I feel really comfortable with the putter on these greens and if you just get me on the greens, I have a chance."