UNIVERSITY PLACE, Wash. -- Jordan Spieth, trying to become only the fourth player since 1960 to win the first two legs of the Grand Slam, squandered three birdie chances late in the third round at the U.S. Open and had to settle for a 71.
The Masters champion's missed opportunities led to a four-way tie at the top of the leaderboard Saturday, with Spieth joining Dustin Johnson, Branden Grace and Jason Day at 4 under.
The co-leaders had tough moments. Along with Spieth's stumbles, Johnson twice smashed driver that set him up for birdies down the stretch and couldn't convert in his round of 70. Grace overcame a rough patch in the middle of his round -- three bogeys in five holes -- to shoot 70.
Day wasn't sure he would even play in the third round. He collapsed to the ground Friday in a frightening moment and delivered one of his best rounds Saturday considering the situation.
For everyone else, it was a matter of hanging on.
Spieth, Johnson and Grace each had the lead at one point on the front nine.
Spieth holed a pair of 35-foot birdie putts early and stretched his lead to three shots until he gave them back with a pair of three-putts, slapping his knee at the mistakes. He held on with some key pars, rolled in a birdie at the 15th to get back into a share of the lead and then wasted three great opportunities -- three putts from just off the 16th green for a par, a missed 10-foot birdie on the 17th and a 12-foot birdie putt that missed on the final hole.
"I didn't have my best stuff today but still tied for the lead, and I've had my best stuff at times this week, and I'm pretty sure I know where it is and how to get it tomorrow and get ready to go," Spieth said.
On Sunday, Spieth will try to join Tiger Woods (2002), Jack Nicklaus (1972) and Arnold Palmer (1960) as back-to-back winners of the season's first two majors.
Grace has been steady. He had three birdies and three bogeys Saturday and through 54 holes has hit 44 greens in regulation; only Jason Dufner and Beau Hossler have hit more.
"I'm stoked. I can't wait. Tomorrow is going to be a good one," Grace said. "This is what we play golf for. It's a dream to lead a tournament like this, or tying the lead."
Johnson gets a fourth shot at his first major. He also wasted good birdie chances with his power -- a tee shot that landed on the front of the green at the 372-yard 16th hole (three-putt par) and a big drive on the par-5 18th. He hit 3-iron into a bunker and made par.
He also was in position to win the 2010 U.S. Open at Pebble Beach, the 2010 PGA Championship at Whistling Straits and the 2011 Open Championship.
"I've been in the situation a few times, so I know how to handle myself," Johnson said. "I know what it takes to get it done. And tomorrow I just need to go out there and focus one shot at a time. And we'll see what happens."
Day and Johnson will tee off together at 6 p.m. ET, just ahead of a Spieth-Grace pairing.
Louis Oosthuizen, meanwhile, set himself up for a shot at U.S. Open history. No one since World War II has ever shot 77 in the first round of the U.S. Open and gone on to win. Oosthuizen was part of that horror show with Woods (80) and Rickie Fowler (81) in the opening round. Oosthuizen figured he would be watching the weekend at his home in Florida. Instead, he shot 66 to make the cut. Then the South African shot another 66 on Saturday and was at 1-under 209.
"A few little things this morning on the range, found a bit of a swing with my driver and seemed to sort of go from there on the rest of my game," Oosthuizen said. "And today I hit it really close on a lot of holes. Could have been probably a lot lower."
Cameron Smith of Australia had a 69 and joined Oosthuizen at 209, along with Shane Lowry of Ireland (70) and J.B. Holmes (71).
The number of players under par kept dropping -- 25 after the first day, 16 after the second and only eight going into the final day.
Rory McIlroy was losing hope in this major. He shot a 70 and was at 4-over 214.
"Whenever you start to miss a couple, you start to get a little tentative," McIlroy said. "You start to doubt yourself. You start to doubt the greens a little bit. And then it just sort of -- it snowballs from there. I holed a few nice ones early on, but once I missed a couple, it got into my head and couldn't really get out of it."
Phil Mickelson lost his bid at the career Grand Slam with a 77 that put him at 10-over 220.
The Associated Press contributed to this report.