Bryson DeChambeau's bid to run away with the BMW Championship came undone on the back nine on Saturday, leaving the big-hitting American tied with Patrick Cantlay heading into the final round.

The leading pair had a three-shot lead over South Korean Im Sung-jae in the second of three events in the US PGA Tour's FedEx Cup playoffs.

DeChambeau started the day with a one-stroke lead after a scintillating 60 on Friday, and pushed his lead to as many as four strokes after another sizzling front nine that included two birdies and back-to-back eagles at the fourth and fifth.

But after spinning his approach to two feet for a birdie at 11, DeChambeau found himself paying the price for errant shots, finding the water with his second shot on the way to a bogey at the par-five 12th and dunking his tee shot at 13 on the way to a double bogey.

He clawed back a shot at the 14th, but gave it back with a bogey at 15.

In deep rough off the tee at the par-five 16th, DeChambeau managed to pick up a birdie after hitting his second shot from the right rough to within a foot.

He finished with a five-under par 67 for 195, and that was enough for a share of the lead after Cantlay made his first bogey of the day at the 18th to cap a 66.

"Front nine I played really good," said DeChambeau, who said his driver "just didn't feel right" from the seventh hole onward.

"But that's OK. I scraped it around," he said, "got to clean up the driver from today."

Cantlay had made early inroads on DeChambeau's lead with a 16-foot eagle at the second hole. He added a birdie at the third, but after back-to-back birdies at 11 and 12 -- a 13-footer and a tap-in -- he was still two adrift.

But as DeChambeau gave up two strokes at the 13th playing partner Cantlay rolled in a 35-foot birdie putt, following it up with a four-foot birdie at 16 that had kept his nose in front until his closing miscue.

Good spot

"It was another day on an easy, soft golf course, so you needed to make a bunch of birdies," Cantlay said. "I thought I played really well, all in all.

"I didn't make too many mistakes. Played solid, didn't putt as well as I did the first couple days but probably hit it a little better, and I thought it was a good day and I'm in a good spot for tomorrow."

Cantlay said it was "not difficult" to stay patient as DeChambeau built his early lead and electrified spectators with his bid to overpower the Caves Valley Golf Club course in suburban Baltimore, Maryland.

After watching his 25-foot eagle putt drop in the back of the cup at the par-five fourth DeChambeau reached the green with a 307-yard tee shot at the short par-four fifth then drained a 53-foot eagle putt.

"There's nothing I can do at that point," Cantlay said. "I'm just trying to stick to my game plan."

Im moved into solo third place with a six-under 66 that included seven birdies. At 18-under he was one stroke clear of Northern Ireland's Rory McIlroy, Mexico's Abraham Ancer, Spain's Sergio Garcia and American Sam Burns.

Burns joined the group with a hole out for birdie at 18 to cap his 65. McIlroy had seven birdies in his seven-under 65, Ancer had six birdies in his six-under 66 and Garcia had six birdies in his five-under par 67.

World number one Jon Rahm was a further stroke back on 200 after a two-under par 70 that included six birdies and four bogeys -- the last at the 18th.