Isner, Johnson reach Houston quarters
Top seed John Isner and defending champion Steve Johnson moved through to the US Men's Clay Court Championships quarter-finals, while Jack Sock also advanced in Houston.
Isner was relentless as he eased into the last eight, the 2013 champion seeing off Swiss opponent Henri Laaksonen 6-4 6-2 on Thursday.
The big-serving American - who won the Miami Open for his maiden ATP 1000 title - needed just 65 minutes to progress.
Next up for Isner is titleholder and countryman Johnson, who defeated Frances Tiafoe 6-3 6-4 on the red clay.
Johnson saved six of seven break points in the sixth seed's straight-sets win over fellow American Tiafoe.
With 12 aces and three breaks, Johnson reached his second quarter-final of the year, having featured in the quarters en route to the Delray Beach semi-finals.
As for third seed Sock, the 2015 champion beat Horacio Zeballos 6-4 6-4 to earn a showdown with Taylor Fritz.
Sock lost his first nine break points against Zeballos but broke two times to move into the next round.
Fritz, meanwhile, outlasted Ryan Harrison 3-6 6-0 6-3.