Rose had a four-stroke lead at one stage

England's Justin Rose let slip a four-stroke lead as he finished the first round of the BMW Championship one shot behind leader Jonathan Byrd.

Rose carded eight birdies in the first 11 holes but two late bogeys saw him card a six-under 65.

Ian Poulter shot a three-under 68, but Luke Donald struggled to a 76.

Byrd birdied three of his final four holes to lead Rose and Colombian Camilo Villegas by one stroke, with Tiger Woods equal seventh on four under.

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Woods was challenging for the lead when he arrived at his 16th hole, the par-four seventh.

However, his drive stopped in the rough 112 yards from the hole, leading to the world number recording his only bogey.

"I just had that one bad hole, but other than that it was a pretty good day," he said.

"You felt like you had to shoot something in the mid 60s, or else you were just going to get left behind. You just knew guys were going to tear it apart."

World number 15 Rose, who is still seeking his first victory in America, was pleased with his opening round at Cog Hill.

"It was a dream start today. I hit a few shots close, had some nice little tap-ins and was four-under through six holes without making a putt," he said.

I felt good about my game and made a few extra putts Tournament leader Jonathan Byrd

"It's always disappointing when you're eight under through 11 and you finish six under but it's certainly not an easy course. There were some tough holes coming in and I was a little bit in between clubs.

"When you're playing well and staying in the moment, you're not getting ahead of yourself and I was doing all those things today. That's one of the reasons I played well."

Byrd's round was his best of the year, and he capped it off with a string of birdies that began with a 25-foot birdie putt on the par-three sixth green and ended with a wedge to six feet of the pin on eight.

"I felt good about my game and made a few extra putts," said Byrd.

"I've played well all year, won a tournament and have had a lot of good finishes."

The BMW Championship is the third event in the four-tournament FedEx Cup, the PGA Tour's end-of-season series which features a first prize of $10m.

The top-ranked 144 players contested the Barclays Classic, with 120 going on to last week's Deutsche Bank event.

A field of 70 are competing in Chicago, with the top 30 progressing to the Tour Championship in Atlanta, between 13-16 September.