Plenty of drama was produced on the first day of match play in the 116th U.S. Amateur Championship at Oakland Hills Country Club on Wednesday. Thirteen of the 32 matches reached the 18th hole, and during one 15-minute span, Brad Dalke and Brandon Pierce each birdied the final hole for walk-off victories.

On Thursday, the 32 remaining players face a potentially long day on the South Course, with the goal to win twice to advance to the quarterfinals.

Here are five Round-of-32 matchups to watch:

Doc Redman, Raleigh, N.C. vs. Sam Horsfield, England (7:50 a.m. EDT)

At No. 2 in the World Amateur Golf Ranking™ (WAGR), the 19-year-old Horsfield, who won the 72-hole stroke-play portion of the recent Western Amateur by nine strokes, is the highest ranked player remaining in the field. He is a two-time U.S. Open qualifier (2015 and 2016) and past semifinalist in the U.S. Junior Amateur (2014). He also has the services of regular PGA Tour caddie Terry Mundy. Mundy serves as Ian Poulter’s caddie, but Poulter is currently injured. Horsfield befriended Mundy several years ago in Orlando, Fla., where Horsfield, a University of Florida sophomore, has resided since his youth.  Redman, 18, doesn’t have the same lofty credentials, but the incoming Clemson University freshman did advance to the Round of 16 in the 2014 U.S. Junior Amateur and tie for second in this year’s Palmetto Amateur. Should Horsfield prevail, a potential Round-of-16 matchup with Dylan Meyer looms. Meyer, who faces medalist Alex Smalley, defeated Horsfield in the Western Amateur championship match, 3 and 2.

Sahith Theegala, Chino Hills, Calif. vs. Sam Burns, Shreveport, La. (8:20 a.m.)

Theegala, 18, a sophomore at Pepperdine University, is hoping to continue the momentum he gained from surviving the 23-for-8 playoff Wednesday morning to grab one of the final spots in the match-play draw. Theegala birdied the second playoff hole – the par-4 11th on the North Course – to earn a Round-of-64 matchup against Justin Suh and then promptly eliminated the No. 4 seed, 1 up. Burns, 20, entered Louisiana State University last fall as one of its more decorated recruits. The American Junior Golf Association named Burns its 2014 Rolex Player of the Year after he won the Junior PGA Championship, AJGA Tournament of Champions and represented the USA in the Junior Ryder Cup. Burns and his partner, Austin Connelly, advanced to the semifinals of the inaugural U.S. Amateur Four-Ball Championship in May 2015. He opened his quest for the 2016 U.S. Amateur title with a 3-and-1 win over Santiago Gomez.

Davis Riley, Hattiesburg, Miss. vs. Curtis Luck, Australia (8:40 a.m.)

Both of these golfers advanced to the semifinals of the 2014 U.S. Junior Amateur, but didn’t face each other; Riley defeated Horsfield, while Luck fell to eventual champion Will Zalatoris. Riley, 19, a sophomore at the University of Alabama, is a two-time U.S. Junior Amateur runner-up (2013 and 2014) who carded a course-record-tying 63 on Oakland Hills’ North Course on Tuesday. But the 2015 U.S. Open qualifier needed 19 holes to eliminate Matthew Wolff in the Round of 64 on Wednesday. Luck, 20, is hoping to keep the recent good play in USGA events by golfers from Perth going. Min Woo Lee won last month’s U.S. Junior Amateur and Hannah Green advanced to the quarterfinals of this year’s U.S. Women’s Amateur. The No. 7 player in the WAGR opened match play with an impressive 4-and-3 win over Andrew Huseman.

Kyler Dunkle, Denver, Colo. vs. Garrett Rank, Canada (9:10 a.m.)

The mid-amateur (25 and older) banner is now carried by the 28-year-old Rank, who this year becomes a full-time National Hockey League referee that will work 73 games. But skating and calling penalties isn’t Rank’s only skill. He was the runner-up to Nathan Smith in the 2012 U.S. Mid-Amateur and he has claimed the last two Canadian Mid-Amateur titles. He also made the 36-hole cut at last month’s RBC Canadian Open. Rank held off Benjamin Griffin, 1 up, in his opening-round match on Wednesday. Dunkle, 19, also had to go the full 18 holes to eliminate Brandon Kida. Dunkle, who is transferring to the University of Utah from Colorado State, is competing in his first USGA championship this week. He won the 2012 Colorado 5A high school title. As a redshirt freshman last season at CSU, Dunkle posted a 73.3 stroke average.

Collin Morikawa, La Cañada, Calif. vs. Doug Ghim, Arlington Heights, Ill. (9:50 a.m.)

Morikawa, 19, is entering his sophomore year at the University of California, where he enjoyed a strong first season on the Berkeley campus with seven top-10 finishes, including a tie for second in the Querencia Cabo Classic in Mexico. His teammate, KK Limbhasut, also advanced to the Round of 32. Prior to enrolling at Cal-Berkeley, Morikawa won the 2015 Trans-Mississippi and 2013 Western Junior. Morikawa opened match play with a 2-and-1 win over 2015 quarterfinalist Austin James, of Canada. Ghim, 20, has enjoyed plenty of previous USGA success, advancing to the championship match of the final U.S. Amateur Public Links in 2014 (lost to Byron Meth in 37 holes) and falling to eventual champion and future University of Texas teammate Scottie Scheffler in the semis of the 2013 U.S. Junior Amateur. As a sophomore at Texas last season, he helped the Longhorns reach the championship match of the NCAA Championship at Eugene (Ore.) Country Club. Ghim also posted a 2-and-1 win on Wednesday over 48-year-old Todd White, the oldest player to qualify for match play.

David Shefter is a senior staff writer for the USGA. Email him at dshefter@usga.org.