ARDMORE, Pa. -- Tied for the U.S. Open lead, Hunter Mahan was on cruise control.
He was the steadiest player for most of Sunday at Merion Golf Club, ripping off par after par after par to stay in the hunt.
Then he hit No. 15.
Mahan's tee shot sailed into the rough. So did his second. Just like that, Mahan's Open run was over.
He fell from a three-way tie for first after his double-bogey on 15 and finished in a four-way tie for fourth with a 5-over 75 and a 285 total. It was his best Open finish since he was sixth in 2009.
"It was brutal out there," Mahan said. "It was tough finishing. But I swung it pretty well, kept my composure."
He scored pars on 13 of his 14 holes with one bogey and tied for the lead with winner Justin Rose and Phil Mickelson going into 15, where he three-putted for double bogey.
He rebounded with a par on 16, but bogeyed the next two holes and lost any chance of winning his first major.
"It's not fun on the last three there," he said. "Phil and I had great chances on 16, and none of us could make it."
Mahan was topped only by Mickelson on Saturday and trailed him by a stroke. They were paired together and went off as the final group on Sunday.
Mahan has yet to win this season and really never has been in the final-round hunt at a major. Still, he saw a silver lining.
"It's good to be there, because every time you get back there again, you feel a little bit more calm," he said. "You know it's still golf. And it's still about hitting good shots."
It was a much different scene in 2010 when Mahan was in tears after the U.S. blew the Ryder Cup in Newport, Wales
Mahan asked then to be in the last singles match, asked to have the pressure of the anchor spot.
But he blew up on No. 17 and conceded to Graeme McDowell to send the Cup back to the Europeans.
Out of that failure, a deeper friendship with Mickelson blossomed. It was Mickelson who patted Mahan on the shoulder and tried to boost his spirits even as tears welled in the Texan's eyes after Wales.
Yes, Mahan wanted that Open trophy, but he ached a bit, too, for Mickelson.
"He's a great leader, and being in golf you don't hear that word very often -- leader," Mahan said. "But he's really a leader in the game and he takes his time out to talk to the young guys. He did it with myself at the Presidents Cup. He really relishes that role and enjoys it.
"He's a great guy to admire."
Mahan's has had major struggles this season, missing two cuts, and finishing no better than 16th in four tournaments prior to the Open.
He was among a group of contenders -- Steve Stricker, Luke Donald, Billy Horschel and Rose -- that had never won a major.
That, of course, changed for Rose on Sunday.
Buoyed by Merion, Mahan feels better about ending that streak soon.
"I stepped on the tee today knowing I was going to win," he said, "And left the 18th green knowing I could win. It's all good."