South Africa’s Louis Oosthuizen plays onto the sixth hole during his final round of the British Open on Sunday at St. Andrews, Scotland.

St. Andrews, Scotland ? OK, everyone together now. You too, Royal & Ancient Golf Club officials and BBC commentators who kept flubbing his name even after he spent all weekend on the world stage at St. Andrews.

Oosthuizen, left, greets wife Nel-Mare and 7-month-old daughter Jana on the 18th green.

It’s WUHST-hy-zen. Louis Oosthuizen.

Or just call him the “Champion Golfer of the Year.” Your British Open titleholder.

The unknown guy with the unpronounceable name finished off the unexpected task Sunday at golf’s ancestral home, and it wasn’t even close.

South Africa’s Oosthuizen captured the claret jug in convincing fashion — a seven-stroke triumph, touring the ancient linksland in a tidy 1-under-par 71 while his pursuers largely stumbled over their golf spikes.

It was the largest margin of victory at a British Open since Tiger Woods romped by eight in the 2000 edition, also contested over the Old Course.

“To win an Open Championship is special, but to win it here at St. Andrews is just something you dream about,” Oosthuizen said. “I’m proud of the way I held my nerves and everything.”

By the final holes, the only question left was whether the 27-year-old European Tour pro would threaten Woods’ scoring record at St. Andrews. A conservative bogey at the Road Hole 17th dashed those hopes, leaving him to finish at 16-under 272, three off the standard.

No matter.

“That was four days of tremendous golf,” said Paul Casey, paired with Oosthuizen in the final group. “He didn’t flinch today. His rhythm looked superb, he drove the ball beautifully, he was very calm. I’ve played with him many times, but that was a world-class performance.”

Before this week, Oosthuizen had made the cut just once in one of golf’s major championships. He finished 73rd at the 2008 PGA Championship — dead last among those who made it to the weekend.

But the Old Course brought out a different side — unflappability. The gap-toothed golfer led by five after a windblown Friday that whipped many of golf’s marquee names, then took a four-shot lead into the final round.

Casey got as close as three strokes after Oosthuizen bogeyed the par-3 eighth, but the South African struck right back — burying a 40-foot eagle putt after driving the green at the 352-yard ninth hole.

“After he made that putt on 9,” caddie Zack Rasego said, “I knew it was in the bag.”

Lee Westwood wound up as the new champion’s closest pursuer, his 70 on Sunday lifting him to 9-under 279. Casey was another shot back after a 75, undone by a triple bogey after driving into a gorse bush at the par-4 12th hole.

Joining Casey at 8-under were Henrik Stenson (71) and Rory McIlroy (68) — whose early week featured a 63 to tie the lowest round in a major championship, followed immediately by an 80 in Friday’s gale winds.

“It’s my favorite golf course in the world,” McIlroy reiterated. “It’s just a pity about Friday.”

Woods finished in a tie for 23rd after a closing 72, unable to break par after Thursday’s opening round. The Open champion in both 2000 and ’05, he had been seeking to become the only man to lay hands on three claret jugs at St. Andrews.

“I did not putt well at all,” said Woods, who switched back to his long-trusted putter after three uneven days. “I’ve got to clean that up before I tee it up again.”

Oosthuizen becomes the fourth South African to win golf’s oldest championship, joining Bobby Locke (four times), Gary Player (three) and Ernie Els (2002, Muirfield). He’s also the first man to capture his first major at St. Andrews since the late Tony Lema in 1964.

“This is absolutely unbelievable,” Els said in a statement. “I could not be happier. Louis is simply a wonderful kid. You cannot find a better one and I am so pleased for him.”

Sunday’s triumph also happened to take place on revered former South African president Nelson Mandela’s 92nd birthday.

“It’s a proud moment,” Resego said. “A great day for South Africa.”