Mickelson was the story of Day 2 before he even teed off, as his first round score of 67 looked like it would give him a big advantage heading into the weekend. But after starting strong, he found himself back with the rest of the pack of leaders after missing a slew of putts which he talked about with the PGA Tour.
Phil: "I got shut out today. I actually played really well. I just didn't capitalize on the birdie opportunities." #USOpen
However, it was his green game that offered the biggest moment of Day 2, as a 25-footer dropped in for birdie on 18 just after the horn sounded to end play for the day. The birdie gave him a tie for the lead.
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Lefty's putter may have failed him at other times Friday in his attempt to win his first U.S. Open, as ESPN's Bob Harig noted, but the impact of his ability to finish strong with a lengthy putt cannot be understated.
Phil hit it great today, made nothing until the hardest hole on the course. Pretty big putt to tie for the lead. #USOpen
Here's a look at the live leaderboard, courtesy of PGA Tour:
Much of the action took place before Lefty even stepped into the tee box, most notably with the super-trio pairing of Tiger Woods, Rory McIlroy and Adam Scott. Woods and McIlroy each posted a 70, and are only four shots back at three-under, which they couldn't have expected upon finishing their round. But Scott struggled.
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The 2013 Masters champion shot five-over for the day, currently sitting at seven-over par for the tournament. Such a number after two rounds of a major wouldn't likely make the cut, but due to the pedestrian scores around the field, his score was safe, and Associated Press golf writer Doug Ferguson was quick to point it out.
Looking like 7-over is safe. That would include the Masters champion.
But even with crowd-favorite Mickelson leading and Scott struggling, the bulk of the talk will continue to revolve around Woods. His improvement from a 73 on Thursday to a 70 on Friday, plus cutting down his bogeys from six in the first round to three in the second, gives glimmers of hope.
However, ESPN's Justin Ray was quick to point out a disappointing stat for Tiger:
Tiger Woods has never won a major when outside the top-5 entering the weekend. T-24th right now.
A big name heading into the weekend was Justin Rose, the South African who has come so close to winning a major so many times. He's shown so far that he'll be a major contender throughout the weekend, and as Iain Carter of BBC Sport proves, it's largely due to his success on the fairways.
Rose has hit 79 % of f'ways so far and 74 % of greens. Both well above average for this US Open. Av'ge 1.81 putts per green. Not do hot.
We can talk about the big names all day, but don't take anything away from Horschel. The 26-year-old hasn't been in many major tournaments (or any big tournaments, really), but he's had a break-through year in 2013 and is showing it so far on a gritty Merion course.
ESPN Stats and Information dug up an incredible statistic from Horschel's second round. Actually, incredible might be an understatement:
Billy Horschel is the 1st player to hit all 18 greens in regulation in a U.S. Open round in the last 15 years. (from @EliasSports)
It seems that every year and in every major, a player like Horschel bursts onto the scene who not many golf fans have heard of and creates buzz heading into the weekend.
All too often, those players fade quickly on Saturday's moving day and Sunday's final round. But when they save their best golf for last, new stars are born.
Could Horschel be one of those next stars, or will he fade like so many before him?
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Where will Billy Horschel stand after Day 3?
Where will Billy Horschel stand after Day 3?
Leader or co-leader
1-3 shots back
4-6 shots back
7 or more shots back
One thing is for sure, though. Merion doesn't seem to be cooperating with any golfer who is looking to have himself a big weekend.
There have been plenty of talking points so far at Merion in this year's U.S. Open. Tiger is in search of ending a five-year drought. Lefty is going for his first ever win in America's championship. Course conditions and a daunting setup at Merion are proving to have a big impact on players.
But if the play of Horschel and the unpredictability of this year's action is any indication, more storylines are bound to start brewing as Saturday and Sunday roll around.