Second seed Justin Thomas continued his barnstorming run at the WGC-Dell Match Play with another emphatic victory in Texas.

Thomas gave South Korean 50th seed Kim Si-woo no chance in their round-of-16 match, plundering Austin Country Club for a 6&5 victory in benign conditions.

Thomas did not lose a hole as he made short work of Kim. He also took only 13 holes to win on Friday, when he beat Francesco Molinari 7&5 on the final day of round-robin competition.

World number two Thomas was joined in the quarter-finals by fellow American, 35th seed Bubba Watson, who also has been in sizzling form this week.

Two-times Masters champion Watson was behind 18th seed Brian Harman early, but turned things around by winning four out of five holes around the turn to seize control.

Watson said his approach to match play was similar to stroke play - try to shoot a good score rather than worry about his opponent's game.

"We're just focused on birdies. If we shoot 67 every day and get beat, we get beat," he said.

Watson's quarter-final opponent will be Kiradech Aphibarnrat, who came from behind to edge American Charles Howell 1-up.

Aphibarnrat was never ahead until the very end when the Thai 28th seed rolled in eight-foot birdies at the final two holes to snatch victory.

"I'm not finished," Thai said of his late comeback.

"(I was thinking) hopefully the putter will be rolling well the last couple of holes. The last two birdies were incredible.

"I just want to enjoy every single minute I spend in Austin."

Aphibarnrat has already won a European Tour match play event this year - the World Super 6 in Australia, where he rode his luck to win.

The quarter-finals will be played later on Saturday.