England's Justin Rose carded a superb 63, eight under par, to claim a two shot lead in the first round of the BMW Championship at Cog Hill.
Rose carded nine birdies and just one bogey to finish one shot outside the course record held by former World Number One Tiger Woods.
Starting on the back nine, Rose picked up shots at the tenth, 11th, 15th and 17th, with his solitary blemish coming on the par four 13th.
The 31 year old then stormed home in 30 with five more birdies to lead by two shots from American duo Webb Simpson and Mark Wilson.
Robert Karlsson produced another strong start with a two under par 69, a score matched by Sergio Garcia among others.
"I certainly probably didn't expect that going out there today," Rose said. "I looked to the weather, looked at the temperature and I thought today was going to be a day to hang in there. Little did I know I was about to play so well.
"It's certainly my best round of the year by a long, long way, and could have been top five, top ten rounds I've ever played for sure. That was really, really good out there."
Rose started the day ranked 34th in the FedEx Cup rankings, but would move up to third with a victory on Sunday.
"(I started the tournament) with the mindset I've got nothing to lose this week," Rose added.
"That's my strategy. That's my attitude.
"Right now I'm not going to Atlanta (the top 30 players qualify for the Tour Championship). I've got everything to gain this week."
Fellow Englishman Luke Donald did not fare so well however, the World Number One struggling to a four over 75 with no birdies, two bogeys and one double bogey.
Masters Tournament champion Charl Schwartzel returned a 73, while world number nine Phil Mickelson carded a 72.
