Second-seeded John Isner advanced to the U.S. Men's Clay Court Championship quarterfinals Thursday, beating Argentina's Leonardo Mayer 6-7 (5), 7-6 (3), 6-3.
Isner set up a match against fellow American Ernesto Escobedo, a 4-6, 6-4, 6-4 winner over Brazil's Thiago Monteiro in the afternoon session at River Oaks. Isner won the 2013 title.
Fourth-seeded Steve Johnson of the United States also advanced, beating Germany's Dustin Brown 7-6 (12), 6-4. Johnson will face fifth-seeded Fernando Verdasco of Spain, a 7-6 (4), 6-1 winner over Argentina's Nicolas Kicker.
Top-seeded Jack Sock of the United States faced Germany's Tommy Haas in the night session. Sock won the event in 2015.