ARDMORE, Pa. (AP) - Short birdie putts were a big deal for Charl Schwartzel and Luke Donald at the 10th hole in the third round at the U.S. Open.
When Schwartzel made his 4-footer Saturday, he became the first player all day to get to 2 under in a tournament where the top of the leaderboard was in constant flux.
Minutes later, Donald reached the same score by converting an even shorter putt at the same hole, a 280-yard par 4 that offered one of the few reliable birdie chances on the tough and tight little course.
The names at the top kept changing. Phil Mickelson and Billy Horschel began the round with a share of first place at 1 under, a score that was as precious as a small piece of shade on a hot day at the club. Soon they were gone, replaced by John Senden and Justin Rose. Then along came Donald to make it a trio.
A few minutes later, 2011 Masters champion Schwartzel was there all by himself with a birdie at No. 7. Donald rejoined him with a birdie at No. 8.
There was also a lot of noise coming from a group farther ahead on the back nine. Nineteen-year-old amateur Michael Kim made four birdies in a six-hole stretch, capped by a 15-foot putt at No. 15 that lowered his score to even par.
Kim, the Jack Nicklaus Award winner as the nation's top collegiate golfer, bogeyed his next two holes, but his score was far better than that of, say, Tiger Woods, who was a 7 over midway through the back nine, in danger of extending his five-year drought without a major championship.
Sunshine was baking a course that had been soaked by heavy rain for a week. The sloping greens were faster and tougher to read. Any putt beyond 15 feet became an adventure, and many closer ones were far from gimmies. Typical of the day: Horschel leaning back in disbelief after missing a 7-foot par putt at No. 5, his expression as colorful as his horizontal-striped shirt.
It became clear that a runaway round to establish a clear leader was unlikely. Quite the contrary. Many scores were running in the opposite direction.
Woods bogeyed three of his first six holes, putting the ball all over the place. He made a nice arcing 15-footer for birdie at No. 1 but missed an 8-footer for par at No. 3. He kept having to bail himself out from tee shots that landed in the rough, although at least he was showing no obvious problems with the left elbow that's been bothering him this week.
Rory McIlroy was faring even worse, with five bogeys on the front nine.
Mickelson and Horschel shared the lead at 1 under after the second round was completed earlier Saturday. In the third round, Horschel saved par at No. 2 by making a putt from the fringe on a hole that ended a remarkable streak of accuracy. Horschel didn't miss a green in regulation during the second round, but his trouble at the 2nd included a hook that went so far left that he had to stand a few feet behind a water cooler to make his next shot.
Neither Mickelson and Horschel could get a handle on the 245-yard par-3 third, Horschel finding the bunker and Mickelson the greenside rough. Both 2-putted for bogey to fall back to even par.
Mickelson bogeyed No. 5 as well, but he later joined the parade of golfers making birdie at No. 10 and picked up a shot at the 11th to get back under par, one shot off the lead.
The average score through two rounds on the par-70 course was 74.7. The cut line was 8 over, saving both defending champion Webb Simpson (5 over) and Masters champion Adam Scott (7 over) and keeping alive, albeit faintly, hopes for a Grand Slam. The third round was played in threesomes teeing off at Nos. 1 and 11 in a tournament that fell behind schedule when storms moved through the Philadelphia area on Thursday.