THE WOODLANDS, Texas (AP) — Davis Riley outlasted Sam Horsfield on the 21st hole Friday in the U.S. Junior Amateur to set up an all-American final against William Zalatoris.

Riley, the 17-year-old from Hattiesburg, Mississippi, who lost in the final last year, rallied to square the match and finished off the 17-year-old Englishman with a par on the third extra hole.

"Tomorrow, I just need to play consistent, keep the ball in front of me, and make a lot of birdies," Riley said. "It's going to be a tough match, because anybody who gets this far is playing well. But you just have to go out there and try to get the win."

The 17-year-old Zalatoris, from Plano, beat Australia's Curtis Luck 1 up to reach the 36-hole final.

"It was a fun day today," Zalatoris said. "This is what you live for, being under the gauntlet."

Riley had birdie wins on the par-5 13th and par-4 16th to pull even with Horsfield in sweltering conditions on the Nicklaus course at The Club at Carlton Woods. They halved 17 and 18 with bogeys, with Riley missing a 3-footer on 18, then split the 19th with pars and halved the 20th with bogeys.

"I just told myself, 'There's nothing I can do about that putt now, so I might as well just shake it off and go to the next hole," said Riley, who also missed a 4-footer on the 20th.

Last year, Riley lost 3 and 2 to Scottie Scheffler at Martis Camp in Truckee, California.

Zalatoris, making his record-tying fifth appearance in the event, won with a birdie on the par-5 18th after Luck won Nos. 14-16 to square the match.

"Even when he won three in a row, 14-16, and then his putt (from the fringe) should have gone in on 17 when it hit the flagstick, I just stayed patient and I knew exactly what I needed to do," Zalatoris said. "Like I've said all week, my ball-striking has held up as well as it has all year."

In the morning quarterfinals, Riley beat China's Andy Zhang 2 up, and Zalatoris topped Zimbabwe's Sean Crocker 3 and 2.

Riley and Zalatoris earned spots in the U.S. Amateur next month at Atlanta Athletic Club.