DELRAY BEACH, February 21, 2019

John Isner remained untroubled, reaching the quarterfinals of the Delray Beach Open by Vitacost.com. The No. 2 seed from the United States beat Lukas Lacko of Slovakia 6-4, 6-3 on Wednesday evening.

Isner saved both break points he faced and converted three of his own nine chances to prevail after one hour and 10 minutes.

“It was a good win,” the 6-10 US-American said of his second consecutive straight-sets win this week. “I think I’m sort of getting more comfortable on this surface, especially with positioning on my return. I think I finally figured that out.”

A night after delivering 23 aces in his first round win against Canadian Peter Polansky, Isner registered 18 aces against Lacko.

“This court kicks very well,” Isner said. “Second set I was very happy with how I played. I was challenging him in a lot of return games. I kept holding my serve and had to save a few break points and had an up-the-line winner.”

Isner will next take on eighth seeded Frenchman Adrian Mannarino, who eased past Denis Istomin from Uzbekistan 6-2, 7-6(3) in one hour and 18 minutes.

“He’s a good player, so it’ll be a good match,” Isner commented on his upcoming task.