Top-seeded John Isner lost to journeyman Dustin Brown in the second round of the U.S. Men's Clay Court Championship on Wednesday night.
It was Brown's first career victory against a top-10 player. He closed out a 6-4, 6-7 (7), 7-6 (4) win with a forehand approach winner.
Isner was the defending champion in Houston. He had 13 aces in the loss.
American Sam Querrey also advanced with a 6-3, 6-4 victory over No. 7 seed Lleyton Hewitt.
Sixth-seeded Juan Monaco beat Somdev Devvarman of India 7-6 (4), 6-2 for his 200th career win on clay.