ARDMORE, Pa. — Merion might be petite, but she sure packs a big punch.
One hundred and fifty six players began this 113th U.S. Open. As darkness fell yesterday over the venerable old course that has hosted more USGA events than any course in America, two players are under par.
Those would be Phil Mickelson, who ended his roller-coaster day by draining a 30-foot birdie putt on his last hole of the day, No. 18, moments after the horn was blown to suspend play for the night, and Billy Horschel.
They are each a mere 1-under through 36 holes.
With play backed up because of Thursday’s weather suspensions, the second round was not completed, with several players still having to complete their round this morning before the third round begins.
The completion of the second round will begin at 7:15 a.m. today.
Trailing Mickelson and Horschel, who shot a 3-under 67 yesterday, which was the low score of the day and tied Mickelson’s first-round score for the low of the tournament, is Luke Donald at even par. Justin Rose and Steve Stricker, who played with Micklelson, are also even through 36 holes.
Tiger Woods, who hasn’t even played that well this week, is a mere four shots out of the lead at 3-over after shooting an even-par 70 yesterday. So, too, is Rory McIlroy, who played with Woods and has posted the same scores as he has.
The average score for the second round was nearly 5-over, and some of the world’s best players missed the cut.
For example, the group of Graeme McDowell, Jim Furyk and Zach Johnson, three players who are not only former major winners but who were considered favorites on this course this week, combined to shoot 40-over par in two rounds — all missing the cut.
“Am I surprised? Absolutely not,” Woods said. “Unless you played practice rounds out here and you’ve seen this golf course, you don’t realize how difficult it is. The short holes are short, but if you miss the fairway you can’t get the ball on the green. And the longer holes are brutal.
“This is probably the stiffest par-3s that we ever face.’’
Indeed, three of the four par-3s played 256, 236 and 246 yards yesterday, looking more like short par-4s than par-3s.
“Every hole at Merion you’re just fighting for par, fighting for par,’’ Mickelson said.
Woods and a number of other players said it was clear by the USGA’s pin placements the last two days “they are trying to protect par.’’
With only Horschel and Mickelson ending the day yesterday below par, the USGA can consider par better protected than the Crown Jewels.
“It’s a testament to a golf course that it doesn’t have to be 7,800 yards to be a great golf course,’’ Furyk said after shooting 16-over. “Merion will always stand the test of time.’’
“It tests every aspect of your game,’’ McIlroy said. “You’re under pressure from that first tee shot. There were people talking about 62 and 63s at the start of the week and, I mean, I never saw that at all. I still think something very little under par is going to win this week. If not that, then around even par.’’
Horschel insisted his day wasn’t as easy as his score indicated.
“I was not in the zone, trust me,’’ Horschel said. “This golf course, even though it’s soft, is still a tough golf course. I don’t [usually] get nervous, but I was nervous on a lot of [shots].’’
What’s scary is this: Merion has not even bared her teeth yet thanks to the seven-and-a-half inches of rain that saturated the grounds this week.
“This course is nowhere close to what the USGA wants, I can tell you that,’’ Horschel said.
“We have a long way to go and these conditions aren’t going to get any easier,’’ Woods said. “They’re going to get more difficult.’’
The only guys laughing will be the players who missed the cut; they won’t have to deal with the mean old lady anymore.
mark.cannizzaro@nypost.com