Mack Champ enlisted in the Air Force when he was 19. On his ride from Amarillo home to Columbus, Texas, Mack got off the bus in College Station. He went to a restaurant and ordered a hamburger. He was denied service at the whites-only counter.

Mack couldn’t play golf in America then, either. He didn’t take up the game until the military took him to Europe. He married his wife, Lulu, and had a son named Jeff in London.

Mack is black. Lulu is white. “He was told if he goes back to Texas and walked off the base with a white lady, he’d go to jail,” Jeff told Golfweek. “That’s how he ended up in California.”

Cameron, like Jeff, is the product of a bi-racial marriage. His grandfather gave him his first set of plastic clubs when Cam was 2.

Thursday, Cam teed off for his first round in a major on his 22nd birthday, at the U.S. Open at Erin Hills. Friday, he vaulted onto the leaderboard while taking the lead in driving distance for the week. Saturday, he began the day at 5 under, two shots off the lead.

He didn’t keep pace with the leaders, shooting a 73 to fall into a tie for 17th. That’s still a remarkable accomplishment.

“I had some nerves and just started doing everything real quick, just got out of my rhythm,’’ he said. “Just too excited and nerves, those two don’t go too well together.’’

Champ is a remarkable ball-striker who outdrove Rory McIlroy and Louis Oosthuizen in practice rounds, sometimes by 50 yards.

His average driving distance of 339.3 yards would easily be the best on the PGA Tour. On his opening tee shot on Saturday, he hit the ball off the heel of his club, had his right hand come off the club, and hit the fairway 300 yards away.

Champ, who qualified for the Open by winning a playoff to take the last spot in his qualifier, went into Saturday hoping to be the first amateur to win the U.S. Open since 1933. He is two shots ahead of Scottie Scheffler, who tied for third in the NCAA tournament last month playing for Texas.

“Obviously, I want to be low am,” Champ said. “Me and Scottie are great buddies. I’m just going to play my game and at the end of the day whatever the score is it’s going to be. If I come out on top, obviously that would be fabulous. But if Scottie can pull a good round and end up beating me, good for him, too.”