Brandt Snedeker collected seven straight birdies en route to an eight-under-par 63 in the first round of the USPGA Tour BMW Championship, while it was another disastrous day for Rory McIlroy.

Snedeker establish a one-shot lead over fellow American Zach Johnson with an impressive score and 15 clear of McIlroy.

Snedeker, ninth in the FedExCup points standings heading into the event, started his round from the 10th tee with three straight pars before surging up the leaderboard with his birdie blitz.

He went on to pick up a further stroke at the sixth and then signed for a superb bogey-free round.

World number four McIlroy had a double-bogey at the par-three 11th and a triple-bogey at the par-four first as he struggled to a 78. 

Graeme McDowell shot a one-under par 70. 

Tiger Woods had a good day at Conway Farms Golf Club in Lake Forest, Illinois, carding a 66 for a share of third alongside Steve Stricker, Kevin Streelman and South Africa's Charl Schwartzel.

Masters champion Adam Scott, winner of the first FedExCup play-offs event this year at The Barclays, was a further stroke back in a group with Nick Watney, John Merrick and Ryan Moore.

The top 30 players in FedExCup points after this tournament progress to next week's Tour Championship at East Lake.

Sweden's Henrik Stenson, the points leader, opened with a respectable one-over 72, but McIlroy and Lee Westwood's hopes of advancing were severely dented by their first-round exploits.

Westwood had seven bogeys and a double-bogey in his birdie-free 80.

"I played well, and I just didn't get much out of that round". - Tiger Woods

Snedeker acknowledged his birdie run had come out of the blue, but was delighted to have started the week with such low score.

"It was one of those days where everything seemed to go right in the middle of the round," he said.

"I got off to a slow start and made a great birdie from off the green on 13 that got everything moving in the right direction, and to roll off seven birdies in a row came out of nowhere. I wasn't expecting it.

"I hadn't been playing the best, to say the least, and to get on a roll like that is always welcoming."

He was not getting carried away, though, adding: "I realise it's going to be a completely different golf course tomorrow if the wind changes.

"I'm excited I got my one low one in me out of the way early and can go out and play some solid golf the rest of the week."

Woods was dangerously placed just three shots off the pace, but was not entirely content with his round.

"I'm not exactly real happy," the 14-time major winner said. "I played well, and I just didn't get much out of that round.

"I certainly wasted a lot of shots out there today. I missed three little short ones in there and then played the par fives even par. That's just not very good."