ST. ANDREWS, Scotland — The last test for Louis Oosthuizen was his second shot to the 17th green at St. Andrews, where the pin was planted perilously behind the Road Hole bunker.

He safely sent his 5-iron through the green and onto the 18th tee, where it stopped about six feet away from where Paul Casey was about to hit. Lee Westwood walked over to the ball and acted as though he was going to smash it back at Oosthuizen.

Even that might not have stopped him Saturday in the British Open.

Oosthuizen opened with a nervous bogey, then settled down quickly on another windswept afternoon for a 3-under 69 that gave him a four-shot lead over Casey and a chance to become the first player in 46 years to win his first major at the home of golf.

Ernie Els called him Saturday morning to wish him and well. Gary Player left him a message at his hotel. Maybe it’s time for the 27-year-old Oosthuizen to start thinking he could be the next South African with a claret jug.

“I don’t think anyone was thinking I was going to be up there,” Oosthuizen said. “You’ve heard yourself, no one can actually say my surname, so they don’t even know who I am out there. It’s great being up there. I just want to enjoy everything about it. I loved it out there. It was great fun for me. And hopefully, tomorrow will be the same.”

Oosthuizen (WUHST-hy-zen) was at 15-under 201. A victory Sunday would make him the first player since Tony Lema in 1964 to win his first major at St. Andrews.

“The Open at St. Andrews would be something special,” Oosthuizen said. “It’s one of those things you dream of.”

Casey went out in 31 when the wind was at its strongest, and mostly into his face. He finished off a bogey-free round of 67 that puts him in the final group of a major for the first time. He was at 11-under 205.

It might be a two-man race between players who have never seriously challenged in a major.

Oosthuizen was seven shots clear of Martin Kaymer of Germany, who had a 68 and was alone in third.