Branden Grace established a commanding three-hole lead over Russell Knox midway through their final Group 11 match at the WGC-Dell Match Play.
Knox came into the clash at Austin Country Club knowing that half a point would be enough to secure him at least a play-off for a place in the last-16, with Grace aware that nothing but victory would do.
Chris Kirk is the other player still in the mix to progress from the group and he was two up against David Lingmerth in their match, meaning if results stayed as they were, a play-off would be required to separate the South African and the American.
Grace and Knox shared their first four holes but back-to-back birdies from Grace, followed by a Knox bogey, put the Commercial Bank Qatar Masters champion in command at the turn.
In Group 3, Race to Dubai winner Rory McIlroy knew that a win against Kevin Na would see him through to the round of 16 but he was one down having played four holes after bunker trouble resulted in a double-bogey on the second.
Adam Scott and Bill Haas were all square in their Group 7 clash after six holes with Haas knowing a half would take him through, while Thomas Pieters was one up against Chris Wood.
Zach Johnson requires just a half to advance from Group 14 and he was two up through five holes against Shane Lowry, but Martin Kaymer was applying some pressure by opening up a four-hole lead over Marcus Fraser.
In the dead rubber in Group 3, Smylie Kaufman and Thorbjørn Olesen were all square after four holes.