Meanwhile, over on the ATP rankings, Jack Draper and Lorenzo Musetti both make major breakthroughs.

It's the first all-American quarterfinal line-up at an ATP event since Orlando in 1991, which was more than five years before any of the Houston quarterfinalists were born.

Tommy Paul and Marcos Giron advanced on Sunday, while Taylor Fritz, Ben Shelton and Brandon Nakashima all won on Monday.