Veteran Lleyton Hewitt is the only Australian left at the ATP event in Washington after a second-round win over compatriot Marinko Matosevic.
Hewitt toppled Matosevic 6-4 6-3 in just over an hour and 20 minutes on Tuesday for a spot in the last 16.
It was the former world No.1’s opening match of the pre-US Open hardcourt tournament, having enjoyed a bye for the first round.
The night didn’t go so well for fellow Australian Bernard Tomic, whose six-match winning streak came to end in the second round.
Tomic went down 6-4 7-6 to Denis Istomin of Uzbekistan, less than a fortnight after winning the Claro Open final in Bogota.
The 21-year-old followed the title triumph with a first-round win over Colombian Alejandro Gonzalez on Monday but couldn’t hold on against 15th seed Istomin.
Countrymen Sam Groth and James Duckworth also crashed out of the event after suffering first-round defeats.
Israel’s Dudi Sela needed two hours to get by lucky loser Groth, prevailing 7-6 3-6 6-4 just two days after losing to John Isner in the Atlanta Open final.
Groth fired 16 aces but won just four of 16 break point chances, while Sela went three for six on his opportunities.
Wildcard Duckworth went down 6-3 7-6 to American Steve Johnson, whose victory earned him a second-round clash with compatriot and No.5 seed Isner.
Sam Querry blasted 17 aces in his 6-4 6-3 win over fellow American Michael Russell for a next round match-up against No.4 seed Kei Nishikori of Japan.