World No. 1 Scottie Scheffler finished 1 up on Davis Riley on Wednesday to claim a first-round win at the World Golf Championships-Dell Technologies Match Play in Austin, Texas.

Scheffler was 3 up after carding an eagle on the par-4 fifth hole, but Riley clawed back, pulling to within 1 up thanks to a birdie on the par-5 12th. However, Scheffler responded immediately, adding another eagle on No. 13 before holding on down the stretch to begin his championship defense.

"I got off to a really good start. Outside of that I didn't really play great and Davis didn't have his best stuff today, either," Scheffler said. "Fortunately I saw a putt go in on 18 to finish out the match, and I did my best to try and stay patient."

South Korean Tom Kim was the victor in the other Group 1 pairing, finishing 2 up on Alex Noren of Sweden with one hole to play. Kim found himself 1 down after the first hole but followed with three straight pars to take the lead. Noren had things tied after a birdie on No. 12, but Kim carded birdies on three of his final five holes to prevent the loss.

"Alex definitely is a fighter and I knew that and I knew it wasn't going to be easy," Kim said. "I just kind of kept my head down, but very fortunate to walk off with a win today."

Rickie Fowler pulled off the upset of the day, closing the first round 2 up on World No. 2 Jon Rahm of Spain. The pairing played 17 holes, with Fowler holding a lead for the final six.

"In golf, just about anyone can beat anyone, especially this week with the guys that are out here," Fowler said. "I know Jon will be tough for the boys next couple matches. I've got to take care of business on my end."

Other notable Wednesday winners included Rory McIlroy of Northern Ireland, who finished 3 up on Scott Stallings with one hole left, Max Homa, who was 3 up on Justin Suh with two holes remaining and Xander Schauffelle, who closed 4 up against Australia's Cam Davis through 15 holes.

Groups with individual standings through one round:

Group 1

Scottie Scheffler, 1-0-0

Tom Kim, 1-0-0

Davis Riley, 0-1-0

Alex Noren, 0-1-0

Group 2

Rickie Fowler, 1-0-0

Billy Horschel, 0-0-1

Keith Mitchell, 0-0-1

Jon Rahm, 0-1-0

Group 3

Rory McIlroy, 1-0-0

Keegan Bradley, 0-0-1

Denny McCarthy, 0-0-1

Scott Stallings, 0-1-0

Group 4

Patrick Cantlay, 1-0-0

Brian Harman, 1-0-0

Nick Taylor, 0-1-0

K.H. Lee, 0-1-0

Group 5

Max Homa, 1-0-0

Hideki Matsuyama, 1-0-0

Justin Suh, 0-1-0

Kevin Kisner, 0-1-0

Group 6

Xander Schauffele, 1-0-0

Aaron Wise, 1-0-0

Cam Davis, 0-1-0

Tom Hoge, 0-1-0

Group 7

Andrew Putnam, 1-0-0

Ryan Fox, 1-0-0

Will Zalatoris, 0-1-0

Harris English, 0-1-0

Group 8

Matt Kuchar, 1-0-0

Si Woo Kim, 1-0-0

Viktor Hovland, 0-1-0

Chris Kirk, 0-1-0

Group 9

Collin Morikawa, 1-0-0

Jason Day, 1-0-0

Victor Perez, 0-1-0

Adam Svensson, 0-1-0

Group 10

Tony Finau, 1-0-0

Adrian Meronk, 1-0-0

Christiaan Bezuidenhout, 0-1-0

Kurt Kitiyama, 0-1-0

Group 11

J.J. Spaun, 1-0-0

Min Woo Lee, 1-0-0

Matt Fitzpatrick, 0-1-0

Sahith Theegala, 0-1-0

Group 12

Jordan Spieth, 1-0-0

Taylor Montgomery, 1-0-0

Mackenzie Hughes, 0-1-0

Shane Lowry, 0-1-0

Group 13

Sam Burns, 1-0-0

Adam Scott, 1-0-0

Adam Hadwin, 0-1-0

Seamus Power, 0-1-0

Group 14

Ben Griffin, 1-0-0

Lucas Herbert, 1-0-0

Tyrrell Hatton, 0-1-0

Russell Henley, 0-1-0

Group 15

Cameron Young, 1-0-0

Corey Connors, 1-0-0

Davis Thompson, 0-1-0

Sepp Straka, 0-1-0

Group 16

Sungjae Im, 1-0-0

J.T. Poston, 1-0-0

Maverick McNealy, 0-1-0

Tommy Fleetwood, 0-1-0