Britain's Justin Rose carded a two-under-par 69 to open up a commanding four stroke lead after the third round of the BMW Championship on Saturday and give himself a shot at the season-ending $10 million jackpot.

With only the top 30 in the FedExCup standings after Sunday's final round qualifying for next week's Tour Championship in Atlanta, Rose arrived at the Cog Hill Golf and Country club sitting in 34th place and needing a good result to secure an invitation.

I'm aware that if I win I go to third, Rose told reporters. We've heard about being in the all important top five going into Atlanta, so it would certainly be a huge win at the right time.

Adopting a gambler's all-or-nothing approach, Rose surged clear of the field with a red-hot putter and some daring shot-making to finish the round at 13-under 200.

Australian John Senden was outright second at nine-under after recovering from a horrendous start to his third round. He bogeyed three of his first five holes but rallied on the back nine picking up four shots for a 70.

Disappointing start to the day, admitted Senden. I knew even if I dropped a couple shots, as I did, I didn't really lose that much ground.

I just knew that if I handled myself out there, I could fight back to whatever the score was and I was able to go out there and do that.

Lurking a further shot back is another Australian, Geoff Ogilvy, who needed a birdie on his final hole at the Deutsche Bank two weeks ago just to earn a spot in the 70-man field for the BMW.

The former U.S. Open champion made the most of his opportunity by returning a 68 to join American Bill Haas (69) five shots off the pace.

Rose started the round tied for the lead with American Mark Wilson but after back-to-back birdies at the fourth and fifth, he had the lead to himself for the rest of the day.

The Englishman displayed his willingness to roll the dice on the par four seventh when his tee shot cut left, bounced off the cart path and rolled to a stop deep in the woods.

Instead of safely punching out, Rose gambled and went for the green landing just on the fringe to save par.

Rose's only miscue on a brilliant late Summer's day was a bogey at the 12th but he hit back with a birdie at 13 then held steady while his challengers crumbled.

Wilson's day unraveled with back-to-back bogeys at 12 and 13 followed by a double-bogey at 16. He finished with a 77 to be tied for seventh with world number one Luke Donald, Sergio Garcia, Jim Furyk and Brandt Jobe.

I ruined that opening round, obviously if I had shot something just halfway decent I'd be right in the mix, said Donald, looking back at his opening 75.

Obviously Justin is playing very well and it's kind of in his hands.

The top 30 in the FedExCup standings after Sunday's final round will qualify for next week's season-ending Tour Championship in Atlanta, where a $10 million bonus will go to the overall points champion.