Vasek Pospisil and Marcos Baghdatis won three-setters at the Atlanta Open, while Go Soeda caused another upset.
Seeds Vasek Pospisil and Marcos Baghdatis progressed at the Atlanta Open, but the in-form Adrian Mannarino bowed out first-up to Go Soeda.
Soeda, fitter for his first-round win over Alexandr Dolgopolov, enjoyed a 6-2 6-4 victory over fourth seed Adrian Mannarino, who was playing his first match since his run to the Claro Open Colombia final last week.
Mannarino received a bye past the first round, but the extended rest was still not enough for him as Soeda advanced to his first ATP World Tour quarter-final since January 2013.
Soeda will take on seventh seed Gilles Muller for a spot in the semi-finals - co-incidentally, the Japanese's most recent appearance in the last four of an ATP tournament was against Muller in Atlanta three years ago.
Muller won through to the last eight with a 6-3 6-2 victory over Jared Donaldson at the ATP 250 hard-court event.
Second seed Pospisil was pushed by Lu Yen-hsun, but prevailed 6-4 6-7 (3-7) 6-4 over the Chinese Taipei number one - the world number 29 powering down 24 aces in the two-and-a-half-hour contest.
Baghdatis, seeded fifth, came from a break down in the third set to surpass Sam Groth, earning a 7-5 3-6 6-3 result to tee up a quarter-final against Pospisil.
The Cypriot trailed 2-0 against power-server Groth, but Baghdatis was able to reel off five straight games - breaking the Australian's serve twice in succession to regain the ascendancy.
In first-round action, Radek Stepanek and Ricardas Berankis both had straight-sets wins.
Stepanek booked a clash with top seed John Isner courtesy of a 6-2 6-2 win over American wildcard Christopher Eubanks, while Berankis dismissed Tim Smyczek 6-4 6-4.