Australia's Jordan Thompson is through to the quarter-finals of the Atlanta Open after a hard-fought straight-sets win over Peter Gojowczyk.
Thompson sent down 18 aces in a 7-6 (8-6) 6-4 win over the German.
The Sydneysider will now meet the in-form Brandon Nakashima for a place in the last four.
Nakashima upset top-seed Milos Raonic from Canada 5-7 6-3 7-6 (7-4).
Trying to join them in the quarter-finals is compatriot Nick Kyrgios, who beat Kevin Anderson in the first round.
Kyrgios is up against Cameron Norrie, who last week beat Nakashima in the final of the Los Cabos Open for his maiden Tour win.
Another to advance to the last eight is No.5 seed Taylor Fritz.
The American beat fellow countryman Steve Johnson 6-7 (7-5) 6-4 6-1.