Sam Burns fires career-low 61 to secure one-shot lead at The American Express

Burns' career-low round leaves him on 17 under par, one shot ahead of fellow American Michael Kim with South Korean's KH Lee and American amateur Nick Dunlap a further shot back.

A pair of eagles and seven birdies had put Burns in with a chance of breaking 60, but he could only par the last two holes.

"Overall just a really solid day," said Burns. "I hit a lot of quality shots and was able to make some putts."

On missing out on a 59, he added: "Based off the scores, obviously everybody's shooting some good numbers, so I think (I was) just trying to keep pace and trying to hit as many quality shots and get as many looks as possible."

Dunlap, who plays at the University of Alabama, fired a 65 at the Stadium Course – one of three being used for the tournament – to follow his opening 64.

"I've been playing some good golf recently and just tried to stay in that same mindset," he said. "Obviously, it's going to be a kind of a shoot-out, it seems like, so pedal to the metal and try to make some putts."

A group of six, including American Ryder Cup star Patrick Cantlay and joint overnight leader Alex Noren of Sweden, sit on 14 under par.

Ireland's Shane Lowry shot a second round of 67 to lie seven shots off the lead.

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