Los Angeles - World No 1 Jordan Spieth cruised to his second WGC Match Play win of the week on Thursday, downing France's Victor Dubuisson 5 and 4.
As in his 3 and 2 triumph over Jamie Donaldson at Austin Country Club on Wednesday, Spieth got off to a quick start and never trailed.
He went 3-up after birdies at the third and fifth, maintaining that cushion until his lone setback of the day, a double bogey at the par-three 11th.
It proved only a hiccup, as Dubuisson failed to notch a single birdie and lost the final three holes of the contest.
"Been able to flight the ball nicely," Spieth said. "I had one bad swing on 11, but really played solid golf.
"Really thought I'd be five or six up at the turn, and Victor made a couple of long putts to tie the holes.
"But that's what he does best. Very pleased to get today done with."
Spieth needs only to halve his match against Justin Thomas on Friday to advance to the knockout round of 16.
World number two Jason Day also needs only to halve his final round-robin match on Friday to advance after a 5 and 3 victory over Thailand's Thongchai Jaidee, while defending champion and third seed Rory McIlroy will duel Kevin Na to advance from their group after both notched two wins in the first two days.
Day showed no sign of the back injury he suffered in his 3 and 2 win over Graeme McDowell a day earlier, crushing his opening drive 380 yards en route to an eagle at the first hole against Thongchai.
He had five birdies in his last seven holes to pull away.
"Didn't really know if I was going to play today," said Day, who was careful to keep up his stretching exercises throughout the round. "It was kind of up in the air ... A little pain but for the most part pretty good."
McIlroy defeated Smylie Kaufman 3 and 1 in a tight match that saw each player twice hold and lose a 1-up advantage over the first 13 holes.
McIlroy squared the match at the 13th and went 2-up with pars at 14 and 15. After they halved the 16th with pars, Kaufman was unable to get up and down at 17 and conceded.
"It was a little scary at the start of the match," McIlroy said, adding that he expected "a little bit more intensity" in the winner-take-all match against Na.
Na opened his match against Thorbjorn Olesen with three birdies in his first nine holes en route to a 3 and 2 victory over the Dane.
"I've been striking the ball very well," Na said. "I haven't made too many mistakes. I haven't made too many bogeys. Today I was three birdies no bogeys for the first nine holes, in these conditions that's very good."
As on the first two days, Friday's matches can be halved. If two more players in a group share the lead, they will play a stroke-play, hole-by-hole playoff to determine who advances.
Eighth-seeded Dustin Johnson bounced back from an opening day defeat to beat Thailand's Kiradech Aphibarnrat 5 and 4.
Johnson birdied two of the first four holes and led after every hole.
"Today I drove it a little bit better," Johnson said. "I holed a couple of putts, just really had a lot of putts to win holes whereas yesterday I had a lot of putts to tie."
British Open champion Zach Johnson notched a big win, downing former world No 1 Martin Kaymer of Germany 8 and 6.
"Today I got up early and just never let go," said Johnson, who with his 4 and 3 victory over Marcus Fraser on Wednesday has played just 27 holes in his first two matches.
World Golf Championships Match Play round-robin scores on Thursday at Austin, Texas (x-denotes seeding):
Jordan Spieth (USA x1) bt Victor Dubuisson (FRA) 5 and 4
Jamie Donaldson (WAL) bt Justin Thomas (USA) 2 up
Jason Day (AUS x2) bt Thongchai Jaidee (THA) 5 and 3
Paul Casey (ENG) v Graeme McDowell (NIR) halved
Rory McIlroy (NIR x3) bt Smylie Kaufman (USA) 3 and 1
Kevin Na (USA) bt Thorbjorn Olesen (DEN) 3 AND 2
Bubba Watson (USA x4) bt Emiliano Grillo (ARG) 2 up
JB Holmes (USA) v Patton Kizzire (USA) halved
Rickie Fowler (USA x5) v Scott Piercy (USA) halved
An Byeong-Hun (KOR) bt Jason Dufner (USA) 2 up
Adam Scott (AUS x6) bt Chris Wood (ENG) 3 and 2
Bill Haas (USA) bt Thomas Pieters (BEL) 4 and 2
Justin Rose (ENG x7) v Anirban Lahiri (IND) halved
Matt Kuchar (USA) v Fabian Gomez (ARG) halved
Dustin Johnson (USA x8) bt Kiradech Aphibarnrat (THA) 5 and 4
Jimmy Walker (USA) bt Robert Streb (USA) 4 and 3
Patrick Reed (USA x9) bt Matthew Fitzpatrick (ENG) 4 and 3
Phil Mickelson (USA) bt Daniel Berger (USA) 1 up
Billy Horschel (USA) bt Danny Willett (ENG x10) 3 and 2
Brooks Koepka (USA) bt Jaco van Zyl (RSA) 5 and 4
Branden Grace (RSA) bt David Lingmerth (SWE) 4 and 3
Russell Knox (SCO) bt Chris Kirk (USA) 2 and 1
Hideki Matsuyama (JPN x12) bt Soren Kjeldsen (DEN) 4 and 2
Rafa Cabrera Bello (ESP) bt Kevin Kisner (USA) 4 and 3
Ryan Moore (USA) bt Sergio Garcia (ESP x13) 1 up
Lee Westwood (ENG) bt Marc Leishman (AUS) 1 up
Zach Johnson (USA x14) bt Martin Kaymer (GER) 8 and 6
Shane Lowry (IRL) v Marcus Fraser (AUS) halved
Brandt Snedeker (USA x15) v Danny Lee (NZL) halved
Charl Schwartzel (RSA) bt Charley Hoffman (USA) 3 and 2
Louis Oosthuizen (RSA x16) bt Bernd Wiesberger (AUT) 2 and 1
Andy Sullivan (ENG) bt Matt Jones (AUS) 3 and 1