The chubby Californian with braces on his teeth stunned the galleries at The Olympic Club when he birdied the first hole -- the 11th of his round -- and suddenly he was ahead of the field, including the biggest name in world sport.

It didn't last that long as a bogey at the second and a double bogey two holes later drew him back to the chasing back.

Still by the end of the day he cme in with a 73 to go with his opening 70 and he comfortably made the cut for two more rounds at the weekend.

Hossler admitted that finding himself leading the US Open had been an experience.

"I was pretty excited about it, but then again I had another 40 holes at least to be playing in the tournament," he said.

Asked what he would have said if someone had told him as a golf fan that a 17-year-old kid would be leading the US Open, Hossler replied: "I would probably tell them they're nuts."

Hossler though is no ordinary 17-year-old golfer.

He has been something of a golfing prodigy for years down in his San Diego home and was the world junior champion in 2011.

He also qualified for last year's US Open at Congressional and at 16 was the youngest player in the field, eventually missing the cut.

He was set to be the youngest player again this year until 14-year-old Andy Zhang of China got a late call-up on Monday.

Zhang's historic US Open appearance, however, ended after two rounds on Friday, but the Beijing-born 14-year-old departed The Olympic Club cherishing an "exciting, unforgettable" experience.

"Everything I did, I had never done it before, and it's just a great experience," said Zhang.

Zhang carded a 78 on Friday for a 157 total. AFP