PONTE VEDRA BEACH, Fla. – The birdie putt on the seventh hole Sunday was from 24 1/2 feet. When it dropped, Si Woo Kim knew he stood alone atop THE PLAYERS Championship leaderboard. Then something unexpected happened in the pressure-packed environment on one of golf’s most challenging tests.

Kim got comfortable.

Wait, let’s amend that.

Kim – the youngest active player on the PGA TOUR — got comfortable.

Comfort is not supposed to be an option, not here, not at TPC Sawgrass, and especially not for 21-year-olds with limited experience in these matters. THE PLAYERS Stadium Course is meant to rattle your cages, test your mettle, fray your nerves. But on a Sunday afternoon when the heat is usually ramped up, Kim became the coolest player on the course. Calm. In control.

“Once he got the lead,” said his caddie, Mark Carens, “that was the least pressure he felt.”

So for his final 11 holes, while his chasers struggled to keep pace and make him sweat, the Korean-born Kim — who now lives in Dallas, Texas – offered up a steady ship, deftly relying on his scrambling ability to bail him out of any precarious situations. He never stumbled, eventually producing a bogey-free 69 and a 10-under total – good enough to make him the youngest champ in PLAYERS history.

The statistic that most reflects his winning round was easy to find: Kim missed 10 greens in regulation, and successfully scrambled each time.

“If you are on your game and playing well, that’s the things you do,” said Louis Oosthuizen, his playing partner Sunday. “You up-and-down when you’re in trouble. You don’t give shots away. If you can do that around this golf course, you can outscore everyone.

“And he played like someone that was doing it for five or six years, like it was just another round of golf. … Never once did he look flustered.

That’s surprising, given his age. But then, he seems to be a player who’s ahead of the curve.

Kim gained his TOUR card through q-school at age 17 1/2 – and then had to wait a half-year before reaching the mandatory age of 18 to play on TOUR. After spending two years on the Web.com Tour, he regained his TOUR card for the 2015-16 season and made a big early impression on his caddie. In his fourth start, he opened with consecutive bogey-free rounds (sound familiar?) en route to a tie for 17th.

“It was unbelievable,” Carens said.

Then at the Wyndham Championship last August, in just his 23rd start on TOUR, Kim shot a second-round 60 – he missed a 50-foot putt on his final hole for a 59. He eventually won that week in convincing fashion, by five strokes in a final round that seemed eerily familiar to how THE PLAYERS unfolded. Once Kim snagged the lead, he never let it go.

He credits the week at Sedgefield with helping him deal with Sunday’s pressure. He said knowing he had a two-year exemption on TOUR freed him up to be more aggressive. (Of course, by winning THE PLAYERS, he now has another five years.)

“Because of that experience,” Kim said through his interpreter, “I could be relieved and I could be very stable. I just focused on myself and I didn’t try to think about others’ scores.”

There wasn’t much to think about, honestly. Oosthuizen and Ian Poulter supplied the most pressure, both making their biggest moves at the par-5 11th. Oosthuizen eagled the hole to go to 7 under; Poulter birdied it to reach 9 under. But Poulter quickly gave the stroke back on the next hole and Oosthuizen stumbled with consecutive bogeys.

Both had the edge on Kim in experience, especially in dealing with intense situations – Oosthuizen’s an Open champ, Poulter’s a Ryder Cup star. But they could not match Kim on Sunday at TPC Sawgrass, instead finishing tied for second.

“You have to take your hat off,” Poulter said. “You have to respect some good golf, and that’s exactly what he’s done.”

The performance this week speaks for itself, but in some ways, Kim’s win was most unexpected.

Consider his Strokes Gained numbers. Ranked 205th on TOUR Off-the-Tee. Ranked 203rd in Approach-the-Green. Ranked 183rd in Putting. Ranked 204th Tee-to-Green. Ranked 203rd Total. His only solid category was Around-the-Green, in which he ranked 41st.

The Golf Channel’s Brandel Chamblee called it “perhaps the greatest upset you’ll ever see” going strictly on statistics. Yet, added Chamblee, TPC Sawgrass “puts everybody on edge, pretty much turns it into a scrambling contest – and he won it.”

But perhaps we shouldn’t view this win as unexpected. Perhaps Kim is the next great Korean star, following in the footsteps of another PLAYERS champ, K.J. Choi. After all, at age 21, he’s done something that not even his fellow 20-somethings Jordan Spieth and Rory McIlroy can claim – winning at TPC Sawgrass.

Unlike Spieth and McIlroy, though, Kim must one day put his golf career on hold to fulfill the mandatory military service for his country. Considering how he played this week, how bright his future is now, it will be a shame to see him go.

Hopefully it won’t happen soon. Plenty of opportunities – big opportunities – await, including the Presidents Cup later this year. The International Team appears to have a new star to lean on.

“He’s still young and he was just so calm today,” said Oosthuizen, an International fixture. “He’s going to be great to have as a teammate.”

Having just spent 18 holes with the young man, it’s evident Oosthuizen would rather be playing with him than against him.