RIO GRANDE, Puerto Rico (AP) — Ricky Castillo made back-to-back birdies right after 18-year-old Blades Brown came undone with one bad hole, closing with a 5-under 67 to win the Puerto Rico Open for his first PGA TOUR title.

Brown, trying to become the youngest PGA TOUR winner in 95 years, had a one-shot lead with six holes to play when he went from a bunker to the water and made triple bogey.

Castillo, playing in the final group behind Brown, holed a 12-foot birdie putt on the 13th, and then hit a beautiful pitch over the mounds to 5 feet for birdie on the par-4 14th.

Castillo narrowly missed out — by 11 points in the FedEx Cup standings — on getting into the $20 million Signature Event at Bay Hill this week. He headed to Puerto Rico, played bogey-free in the final round at Grand Reserve and earned his way into his first major championship as a pro.

The victory gets him into the PGA Championship. He already was eligible for THE PLAYERS Championship next week at the TPC Sawgrass.

“It's really cool to put into words to be able to win my first event,” Castillo said. “I felt like I wanted to be in Bay Hill and I decided to just come out here and play this and ended up winning, so it all works out in the end. Yeah, surreal week."

He finished at 17-under 271, one shot ahead of Chandler Blanchet, who birdied the final hole for 67.

Brown, who turned pro last year and didn't graduate high school until January, birdied his last hole for a 69 to finish alone in third, his first top 10 on the PGA TOUR.

But it was one hole — the 455-yard 13th — that did him in. It was similar to The American Express in January, when Brown played in the final group with Scottie Scheffler. He put a tee shot into the water on the fifth hole and made double bogey and was quickly out of reach of golf's best player.

This time, he drove into a fairway bunker and his approach to a green with water all the way down the right side drifted well to the right. He took his drop, then got too aggressive with a wedge and the ball trickled over the green. He chipped to 7 feet and missed the putt, taking triple bogey.

Brown had a one-shot lead going to the 13th and was four shots behind when he finished the 14th.

John Daly II, the 22-year-old son of two-time major champion John Daly, started three shots behind and shot 34 on the front nine. But he fell back quickly with five bogeys in seven holes to start the back nine and shot 74.

“I learned that you’ve got to put four rounds together and it’s not easy out here,” Daly said. “But very happy, not mad at all. Just a great day, great week.”

He heads back to Arkansas with eyes on trying to win an NCAA title.

Brown earned his spot in the Valspar Championship at Innisbrook with his first top 10. He already had a sponsor exemption into the event.