By Andrew Both
PINEHURST North Carolina (Reuters) - Phil Mickelson's quest to become the sixth man to win a career grand slam of all four professional majors was hanging by the thinnest of threads after the second round of the U.S. Open on Friday.
"The hole looks like a thimble right now. I'm having a hard time finding it," a crestfallen Mickelson said after suffering a putting nightmare en route to a three-over-par 73 at Pinehurst No. 2.
He looked and sounded like a beaten man and will start Saturday's third round a distant 13 strokes behind tournament leader Martin Kaymer of Germany.
"I'm not overly optimistic," British Open champion Mickelson told reporters. "I'm not going to give up (but) tomorrow I need to shoot six or seven-under to have a realistic chance."
The only players to have clinched all four of golf's modern majors are Americans Gene Sarazen, Ben Hogan, Jack Nicklaus and Tiger Woods, and South African Gary Player.
Mickelson reverted to a conventional putting grip on Friday after an experiment with the claw grip in his previous two rounds on the PGA Tour, but it made little difference.
"The three-putt on (the sixth hole) shook me a little bit," the American left-hander said. "After I've three-putted three or four times, I lose my focus on the other stuff and it really affects my ability to concentrate. I'm just not dialed in."
Mickelson, who turns 44 on Monday, has won the Masters three times, and the British Open and PGA Championship once each, but the U.S. Open has been his nemesis.
He has finished second in his national championship a record six times, including at Pinehurst in 1999 when the U.S. Open was first staged here.
(Reporting by Andrew Both; Editing by Mark Lamport-Stokes)