Nick Kyrgios continued his strong return to clay courts on Wednesday, defeating Tommy Paul 6-4 6-2 to progress to the quarter-finals of the US Men's Clay Court Championships in Houston.

Before Tuesday's victory over Mackenzie McDonald, Kyrgios had not played on clay since his infamous meltdown against Casper Ruud at the Rome Masters in 2019, where he threw a chair across the court and walked off during a change of ends.

The 26-year-old Australian wild card's serve kept him in relative control, saving all six break points he faced in the 70-minute match, as well as serving 10 aces and winning 88 per cent of points on his first serve.

"I had to be locked in today and I knew that I had to serve well," Kyrgios said post-match. "It's probably one of the better matches I've played on clay in my career, so I'm pretty happy with the way I came out here today, just put my head down and went to work.

"I've been serving really well, so I just wanted to keep to good habits."

Having fun in the sun@mensclaycourt | #USClay | @NickKyrgios pic.twitter.com/olanqyBt75
— ATP Tour (@atptour) April 6, 2022

The world number 94 will now face Michael Mmoh, who defeated Sam Querrey 6-2 6-4.

Meanwhile, third seed Reilly Opelka did it relatively tougher in the other all-American clash on Wednesday, coming back from a set down to defeat Mitchell Kreuger 3-6 6-2 6-4.

Opelka came into the match having lost just 13 service games in 19 matches this season, but was broken twice in the opening set against Krueger. The world number 18 has been dealing with a right shoulder injury that forced him to retire at the Miami Open against Francisco Cerundolo.

The 24-year-old still managed 15 aces for the match, including a big serve out wide in the Ad court on match point.

"He played well, I think he came out swinging," Opelka said afterwards. "I think he was free, I wasn't. It's a different situation.

"It was a good opportunity for him to play free and get a win and I'm a guy who hasn't always been the most consistent, especially changing surfaces, so I think it was a good win."

He will face Gijs Brouwer, who progressed past J.J. Wolf with a 6-1 6-1 win.