Next month's U.S. Open course is the toughest in golf, according to world number two Phil Mickelson.

The American left-hander played at Torrey Pines South in California last week and predicted an over-par winning score at the second major of the season.

"Even if it's soft I don't think anything close to even-par will win," Mickelson told reporters after firing a four-under 68 in the Wachovia Championship first round on Thursday.

"I think it's the hardest course in the world, 7,600 yards at sea level."

The 37-year-old Mickelson said the rough was particularly brutal, even by usual U.S. Open standards.

He played the course with two friends, both scratch-handicap amateurs.

"They are two very good amateurs and they shot about 85," said triple major winner Mickelson. "They had a better-ball score of 80."

Torrey Pines hugs the Pacific Ocean in La Jolla, a suburb of San Diego.

The U.S. Open, a championship Mickelson has yet to win, starts on June 12.

Reuters