It's the second round that recently has given Bradley fits on the Copperhead course.

Bradley ran off four birdies over his last five holes, finishing with a 20-foot birdie putt on the 18th and a two-shot lead on a day of low scoring not typically seen at this PGA Tour stop.

"Basically zero stress the whole day," Bradley said. "I know that I'm going to have some bogeys and some stress coming. But as for today, I played so good and it feels good to go around a course like this and shoot that score."

Riviera winner Max Homa had eight birdies and was in a large group at 66 that included Emiliano Grillo and Ryan Moore.

It wasn't a breeze for everyone. Dustin Johnson, the No.1 player in the world, didn't make a birdie over his final 12 holes and had to settle for a 71. Johnson hasn't finished in the top 10 in just over two months and first has to worry about making the cut.

Justin Thomas celebrated his 28th birthday by opening with an eagle and coming inches away from a hole-in-one, but he stalled on the back nine and shot 69.

Phil Mickelson, playing at Innisbrook for the first time since 2004, shot 73.

"Basically zero stress the whole day ... I played so good and it feels good to go around a course like this and shoot that score." – Keegan Bradley

As for Bradley, this is the fifth straight time he has started the Valspar Championship in a tie for sixth or better. He has missed the cut twice – including in 2016, when he shared the 18-hole lead – and has cracked the top 30.

Bradley had his game dialled in from the start, and especially at the finish. He made birdie the only time he missed a green, just short on the par-3 15th. He had the four-foot par putt and another one from just over three feet. The other nine par putts were 20 inches or shorter.

"I didn't really come close to making a bogey, so that was a really fun day to be out there and playing," Bradley said.

Paul Casey, trying to become only the fourth player in the last 40 years to win the same tournament three straight times (Tiger Woods did it on six occasions), overcame a rough start with a 68.

He also came inches away from an ace on the 4th hole, with one fan jumping out of his chair prematurely. It caught the lip. He made a two.

Australians Aaron Baddeley and Rhein Gibson both shot one-over 72s to be the leading Australians in the field.

They are tied 88th and in need of a good second round to make the cut.

- Doug Ferguson, Associated Press