Former champion Rory McIlroy crashed out of the WGC-Dell Technologies Match Play despite winning a match without hitting a single shot.
McIlroy, who lost his opening contest in group two to Denmark's Soren Kjeldsen, was due to face American Gary Woodland on Thursday, the man he beat in the 2015 final.
However, Woodland withdrew from the £7.8million event at Austin Country Club due to a "personal family matter", leaving Kjeldsen - who would have played Woodland on Friday - needing only to halve his match with Argentina's Emiliano Grillo to advance to the last 16.
And Kjeldsen, who had never previously won a match in the tournament, won four holes in succession from the 10th on his way to a 4&3 victory to book his place in the knockout stages.
A statement released by Woodland's management company read: "Due to a personal family matter, Gary Woodland must withdraw from the World Golf Championships-Dell Technologies Match Play. We ask that you respect his family's privacy at this time."
Speaking after his round, Kjeldsen told reporters: "I'm very pleased, but actually not happy about Gary and what's going on with Gary. I don't know the details, but Gary is one of the nicest guys out here. So we wish him all the best, and his family all the best.
"I was in a very, very, very tough group. And I got through that."
A day after defending champion Jason Day pulled out of the event to spend time with his mother as she undergoes treatment for lung cancer, Italy's Francesco Molinari also withdrew with a wrist injury after suffering a 5&3 defeat to Thongchai Jaidee.
That meant Sweden's Alex Noren, who was due to play Molinari on Friday, was guaranteed to advance from group eight having beaten Bernd Wiesberger 3&2 to claim his second win of the week.
In contrast, Masters champion Danny Willett was eliminated with a game to spare after being thrashed 6&5 by American Bill Haas, while world number one Dustin Johnson made it two wins out of two by beating Martin Kaymer 3&2.
Two-time Masters champion Bubba Watson also showed signs of a return to form with his second win, the left-hander beating compatriot Scott Piercy 4&3.
Watson has not had a top-10 finish since September's Tour Championship and, despite being ranked seventh in the world at the time, was left off the United States Ryder Cup team.
But the world number 17 could be rounding into form at the right time with the Masters just a fortnight away.
"I'm always thinking about Augusta," Watson said. "If there's a major - not a golf tournament, but a major - built for me, where I have a good shot at it, that's it. That's just common sense, right? Everybody knows a lot of the holes go the way that I want to shape it, and there's not high rough."
Watson can book his place in the last 16 by beating Thomas Pieters on Friday, the Belgian Ryder Cup star having lost to Jhonattan Vegas on Thursday.
Two-time major winner Jordan Spieth had also been in danger of an early exit after losing his opening match, but the Texas native kept his hopes alive with a 4&2 win over Yuta Ikeda.
Lee Westwood was handed a win following Day's withdrawal and can force a play-off in group three by beating Pat Perez on Friday, while Kevin Na needs just half a point against Chris Wood after beating Justin Thomas in group six.
But perhaps the most eagerly anticipated match on day three will see Sergio Garcia take on Jon Rahm in an all-Spanish clash to decide the winner of group seven. Garcia beat Kevin Chappell 4&3 while Rahm defeated Shane Lowry 2&1.