World number one Rory McIlroy set up a WGC Match Play showdown with Billy Horschel by beating Brandt Snedeker two up to maintain his 100% record.
The unbeaten Horschel beat Jason Dufner, meaning the winner of Friday's tie will reach the knockout stage.
Lee Westwood will have to beat Jordan Spieth to progress to the last 16 after the pair defeated Mikko Ilonen and Matt Every respectively.
But Ian Poulter went out with a day to spare after losing to Gary Woodland.
The world's top 16 are the leading seeds in as many groups of four players, with only the winners of each group progressing to the knockout stage.
The renewal of McIlroy and Horschel's rivalry will be one of the highlights of the final day of the group stages at Harding Park, reviving memories of the pair's heated clash at the 2007 Walker Cup when the Northern Irishman thought his opponent's celebrations were "loud and obnoxious".
"I know he is going to be amped up to play me and I am going to be amped up to play him," Horschel said in San Francisco.
"We have a track record together and when we have played each other we've played our best golf, and I would not expect anything less on Friday."
McIlroy, 25, saw a two-hole lead disappear after birdies from Snedeker on the 11th and 12th before securing victory with birdies on the 15th and 18th.
In group two, Westwood faces a daunting task against Masters champion and world number two Spieth.
The Englishman recovered from three down after nine holes to beat Ilonen, while the in-form Spieth had 10 single putts in succession to see off Every 4&3.
Poulter was not the only high-profile casualty, with Graeme McDowell, defending champion Jason Day and Henrik Stenson all failing to progress.
Group 1: 1-Rory McIlroy (NI), 18-Billy Horschel (USA), 35-Brandt Snedeker (USA), 53-Jason Dufner (USA)
Group 2: 2-Jordan Spieth (USA), 26-Lee Westwood (Eng), 40-Matt Every (USA), 62-Mikko Ilonen (Fin)
Group 3: 3-Henrik Stenson (Swe), 23-Bill Haas (USA), 42-Brendon Todd (USA), 60-John Senden (Aus)
Group 4: 4-Bubba Watson (USA), 29-Louis Oosthuizen (RSA), 33-Keegan Bradley (USA), 63-Miguel Angel Jimenez (Spa)
Group 5: 5-Jim Furyk (USA), 17-Martin Kaymer (Ger), 44-Thongchai Jaidee (Tha), 59-George Coetzee (RSA)
Group 6: 6-Justin Rose (Eng), 22-Ryan Palmer (USA), 34-Anirban Lahiri (Ind), 56-Marc Leishman (Aus)
Group 10: 10-Sergio Garcia (Spa), 30-Jamie Donaldson (Wal), 39-Bernd Wiesberger (Aut), 54-Tommy Fleetwood (Eng)
Group 11: 11-Jimmy Walker (USA), 27-Ian Poulter (Eng), 46-Webb Simpson (USA), 50-Gary Woodland (USA)
Group 13: 13-Rickie Fowler (USA), 32-Graeme McDowell (NI), 47-Shane Lowry (Ire), 55-Harris English (USA)
Group 14: 14-Matt Kuchar (USA), 31-Hunter Mahan (USA), 41-Stephen Gallacher (Sco), 61-Ben Martin (USA)
Group 15: 15-Patrick Reed (USA), 29-Ryan Moore (USA), 49-Danny Willett (Eng), 61-Andy Sullivan (Eng)
Group 16: 16-Hideki Matsuyama (Jap), 21-Kevin Na (USA), 44-Joost Luiten (Ned), 54-Alexander Levy (Fra)