Webb Simpson carded a spectacular nine-under 61 to grab the first-round lead at A Military Tribute at The Greenbrier on Thursday.

Simpson has saved his best form for the biggest events this season, winning The Players Championship and following it up with a top 10 at the U.S. Open, but he impressed again.

The American's 61 saw him fire a six-under 30 on the back nine at the PGA Tour event, renamed in honour of the United States military involvement at the Greenbrier site.

He even went on 59-watch late in his round, needing a birdie on the last two holes, but he settled for two pars.

Whee Kim shot an eight-under 62 in round one with 10 birdies and two bogeys on the scorecard.

Kim had an eight-hole stretch of either birdie or bogey on the front nine, but he settled down on the back with a bogey-free four-under 32.

Joaquin Niemann, a 19-year-old phenom, continues to climb toward full exemption after a number of solid finishes.

He was hot again on Thursday, the former top-ranked amateur shooting a seven-under 63.

Kelly Kraft shot a six-under 64 and Keegan Bradley led a group who shot a five-under 65.

Phil Mickelson and Kevin Chappell were among a large group at four under. Mickelson shot a four-under 32 on the back nine after struggling on the front.

Jamie Lovemark and Tony Finau led a group at three under. Finau has finished in the top 10 in both majors so far this season.