World No 1 Dustin Johnson and last year’s runner-up Jon Rahm both suffered surprise first-round exits from the WGC-Dell Technologies Match Play,
Johnson followed his opening-day loss to Bernd Wiesberger with a 4&3 defeat to 38th seed Adam Hadwin at Austin Country Club, meaning the defending champion cannot progress from Group 1.
The 33-year-old now faces a dead-rubber against Kevin Kisner on Friday, while Rahm had his elimination confirmed from Group 3 with a game to spare after the world No 3 lost to Chez Reavie.
Rory McIlroy dispatched Jhonattan Vegas 2&1 in Group 6 to ensure he still has a chance of reaching the knockout stages, providing the Northern Irishman defeats Brian Harman in the final round-robin fixture.
Jordan Spieth defeated Haotong Li 4&2 to set up a winner-takes-all clash in Group 4 against Ryder Cup team-mate Patrick Reed, who saw off Charl Schwartzel with a final-hole birdie.
A 2&1 win over Daniel Berger moves Ian Poulter into top spot in Group 9, with the Englishman requiring at least a quarter-final finish to have a chance of securing a late invite to the Masters.
"It's s a great start," Poulter said. "You need to do that in this format. It's so easy to get complacent. My adrenaline is going right now. It's nice to play under that pressure."
Tommy Fleetwood bounced back from his loss to Poulter on Wednesday to thrash Kevin Chappell 7&6 in the same group, the biggest victory of the tournament so far, as Paul Casey tops Group 10 following his 4&2 victory over Kyle Stanley.
Alex Noren saw off fellow European Thomas Pieter 5&4 to leave a head-to-head meeting with Tony Finau to decide the winner of Group 13, while Watson triumphed 3&2 over Marc Leishman to maintain his 100 per cent start in Group 16.
Watch the WGC-Dell Technologies Match Play throughout the week live on Sky Sports. Live coverage continues on Friday from 2.15pm on Sky Sports Golf and 6pm on Sky Sports Main Event.