Steve Marino withdrew prior to the start of his first round on Thursday afternoon with back spasms. He was not replaced in the field because there were no alternates on site at The Greenbrier.

Greg Kraft withdrew due to illness, as well. He was replaced in the field by Glen Day, who shot a 1-over 71.

Jason Bohn is working on what could be a career low – and maybe a course record -- at Colonial Thursday. He's played his first 13 holes in 7 under and owns sole possession of the lead.

Bohn set the tone for his round early with a 12-foot birdie putt on the first hole. His other birdie putts have come from 20, 15, 18, 6, 4 and 13 feet.

The course record at Colonial is a 61 shot by six players -- Keith Clearwater (1993), Lee Janzen (1993), Greg Kraft (1999), Kenny Perry (2003), Justin Leonard (2003) and Chad Campbell (2004).

Bohn, who won his second TOUR event earlier this year, has a solid record at Colonial. He's played in the Crowne Plaza Invitational four times previously and twice has finished among the top 25. He's never missed a cut and has nine rounds in the 60s, including a 65 in the second round last year.