Rory McIlroy and Jon Rahm made impressive starts to the WGC-Dell Technologies Match Play, while Jordan Spieth rallied to secure half a point.
Coming off a win at The Players Championship, McIlroy crushed Luke List 5 and 4 in his opening match in Group 4 at the Austin Country Club on Wednesday.
The Northern Irish 2015 champion went ahead at the second hole and never looked back against his American opponent.
There was a slight upset in the group's other match as South African Justin Harding edged Matt Fitzpatrick 1up after the Englishman bogeyed the final hole.
.@McIlroyRory loves Match Play.
— PGA TOUR (@PGATOUR) March 27, 2019
Strong start to his week. #LiveUnderPar pic.twitter.com/iygE82wQ7k
Rahm, runner-up in 2017, produced the biggest win of the day with a 7 and 5 thrashing of South Korean Kim Si-woo in Group 8.
A record three-time champion of the event, Tiger Woods made a winning start, although he was below his best.
The 14-time major winner overcame Aaron Wise 3 and 1, although only after he had trailed through 10 holes.
World number one Dustin Johnson started his tournament with a convincing 4 and 3 victory over Chez Reavie in Group 1.
The No. 1 seed does it.@DJohnsonPGA defeats Chez Reavie.
— PGA TOUR (@PGATOUR) March 27, 2019
4 and 3.#LiveUnderPar pic.twitter.com/Zw6W8uAISY
Justin Rose edged Emiliano Grillo 2 and 1 in Group 2, while fellow Englishman Paul Casey – in form after a win at the Valspar Championship – brushed past Abraham Ancer 5 and 3 in Group 10.
However, Spieth and Brooks Koepka had contrasting fortunes late as they halved matches against Billy Horschel and Tom Lewis respectively.
Spieth, without a top-10 finish in six events this year, made a birdie at the 18th to earn half a point against Horschel, who was earlier 3up.
After being 3 DOWN ... @JordanSpieth fights back.
— PGA TOUR (@PGATOUR) March 27, 2019
A birdie on 18 and he finishes AS with Billy Horschel.#LiveUnderPar pic.twitter.com/MjkHwIxOcL
Koepka took a lead to the final hole against Lewis, but the Englishman's birdie saw them halve their match.
Two-time champion Jason Day, world number five Justin Thomas and last year's winner Bubba Watson all lost.
Jim Furyk rallied past Day 2up, Thomas was stunned 3 and 2 by Dane Lucas Bjerregaard and Kevin Na edged Watson 1up.
Group 1: Dustin Johnson beat Chez Reavie 4 and 3, Branden Grace beat Hideki Matsuyama 4 and 3
Group 2: Justin Rose beat Emiliano Grillo 2 and 1, Gary Woodland beat Eddie Pepperell 2 and 1
Group 3: Brooks Koepka and Tom Lewis halved their match, Li Haotong beat Alex Noren 5 and 4
Group 4: Rory McIlroy beat Luke List 5 and 4, Justin Harding beat Matt Fitzpatrick 1up
Group 5: Lucas Bjerregaard beat Justin Thomas 3 and 2, Matt Wallace beat Keegan Bradley 1up
Group 6: Bryson DeChambeau beat Russell Knox 3 and 1, Marc Leishman beat Kiradech Aphibarnrat 2up
Group 7: Francesco Molinari beat Satoshi Kodaira 5 and 4, Thorbjorn Olesen beat Webb Simpson 2 and 1
Group 8: Jon Rahm beat Kim Si-woo 7 and 5, Matt Kuchar beat J.B. Holmes 3 and 1
Group 9: Xander Schauffele beat Lee Westwood 1up, Tyrrell Hatton beat Rafa Cabrera Bello 4 and 3
Group 10: Paul Casey beat Abraham Ancer 5 and 3, Charles Howell III beat Cameron Smith 2 and 1
Group 11: Tommy Fleetwood beat Byeong Hun An 3 and 2, Kyle Stanley beat Louis Oosthuizen 3 and 2
Group 12: Jim Furyk beat Jason Day 2up, Henrik Stenson beat Phil Mickelson 2 and 1
Group 13: Tiger Woods beat Aaron Wise 3 and 1, Patrick Cantlay and Brandt Snedeker halved their match
Group 14: Tony Finau beat Keith Mitchell 2 and 1, Ian Poulter beat Kevin Kisner 2up
Group 15: Kevin Na beat Bubba Watson 1up, Jordan Spieth and Billy Horschel halved their match
Group 16: Andrew Putnam beat Patrick Reed 3 and 2, Sergio Garcia beat Shane Lowry 4 and 2