Kisner, aiming for a second consecutive title following his triumph in 2019, overcame Thomas 2&1 to eliminate the world number two from the event at Austin Country Club.

Victory for the American in the group two encounter maintained his 100 per cent record and he will reach the last 16 if he defeats compatriot Matt Kuchar tomorrow.

Kuchar kept his hopes alive with a 1-up win in his clash with South African Louis Oosthuizen.

"I really enjoy the one-on-one competitive nature of the event," said Kisner. 

"I really like knowing what I have to do on every shot compared to a four-day event.

"I kind of get lost in the motions sometimes when it’s a Friday morning or Friday afternoon and everything’s not going perfect. 

"I think you got to grind all 18 holes and that keeps my head in the game."

World number one Dustin Johnson and Robert MacIntyre of Scotland, the 41st seed, are tied for the lead in group one after halving their match today.

MacIntyre had a shock win in his sights when he lead by two with three holes to play, but Johnson came roaring back to avoid defeat.

Johnson, the reigning Masters champion, eagled the 16th and then birdied the next with a 17-foot put to salvage a halve from a thrilling match.

Northern Ireland’s Rory McIlroy, who won this event in 2015, recovered from his loss to England's Ian Poulter yesterday with a dominant 4&3 win against Lanto Griffin of the US.

McIlroy can still qualify from Group 11 but will need results to go his way tomorrow if he is to progress.

The 16 group winners will make it through to the next stage of the tournament, the round of 16, when action moves to a knockout format.