Justin Thomas, who can replace the eliminated Dustin Johnson as world number one with a victory, thrashed Francesco Molinari 7&5 to join Sergio Garcia, Kiradech Aphibarnrat, Charles Howell III, Patrick Reed and Alex Noren in advancing to the knockout stage with flawless 3-0 records.
Spieth dodged some early bullets against Haotong Li, who missed putts inside 8 feet on two of the opening three holes.
Kisner chases the biggest title of his career, having won PGA crowns at Colonial a year ago and Sea Island in 2015. Woods, a three-time champion, has won 33 matches.
"I had a pretty serious conversation with my dad on Monday if I was going to play", Thomas said. Yesterday I could feel it after the round with my driver.
Peter Uihlein seized control around the turn at Austin Country Club, winning the ninth hole with a birdie and the 10th hole when McIlroy made bogey. In his way is Bubba Watson, who is back to playing like the two-time Masters champion.
McIlroy added: "I left myself behind the 8-ball after losing that first match".
Rory McIlroy has been eliminated from the WGC-Dell Match Play after being comfortably defeated 5&3 by diminutive giant killer Brian Harman on Friday. "If I was sick or really sick, me trying to play this week wasn't going to do me any good".
McIlroy was two down after finding two hazards in his first five holes and Harman's deadly approach play and solid putting did the rest.
In a return to form, Ian Poulter beat Louis Oosthuzien 2&1 to win his fourth match on the bounce.
Australian Cameron Smith halved his match with Yusaku Miyazato and will move on to face Englishman Tyrrell Hatton, who beat Charlie Hoffman 3-and-2, in the Round of 16 on Saturday morning. I felt I was positive at times where I could have gone the other way and have in the past.
"You have to give (Thomas) the edge (Sunday), but this course is made for Bubba", NBC golf analyst and two-time U.S. Open victor Johnny Miller said.
"I've had three goes at winning the grand slam and I'd had maybe 12 or 13 majors before I won my first one so you could say the first one was maybe a little bit harder, but I only get one opportunity a year at Augusta". Should Thomas beat Watson in the semifinals on Sunday, he will become the third American to reach number one before the age of 25.
Noren led Smith, the only debutant in the last eight, after every hole.
Kiradech, unbeaten entering the quarter-finals, was level with Watson after nine holes, but lost four straight holes to gift the big-hitting left-hander a semi-final spot.
"I've never made it to Sunday at this golf course, so why not?"