John Isner remains on track for yet another appearance in the Atlanta Open final after reaching the last eight on Wednesday.
The American, the second seed at the ATP 250 event, eased past Vasek Pospisil 6-3 6-4 in the second round.
Isner, coming off a title win in Newport, is a three-time champion (2013-15) and three-time runner-up (2010-11, 2016) at the tournament.
He will face Lukas Lacko in the quarter-finals after the Slovakian brushed past sixth seed Donald Young 6-3 6-1.
Gilles Muller also advanced to the last eight with a hard-fought 6-4 6-7 (1-7) 6-3 win against Quentin Halys.
Wimbledon quarter-finalist Muller will face qualifier Tommy Paul, who beat Malek Jaziri 6-7 (5-7) 6-4 6-3.