Unseeded Australian Bernard Tomic continued his good run of form with a 6-1 7-5 win over fifth seed Alexandr Dolgopolov in the Memphis Open second round on Thursday.
Tomic - ranked 49th in the world - was too strong for the Ukrainian on the hard indoor courts in Memphis, fending off seven break points as he closed out the match in a little over an hour.
The 22-year-old, who will meet Donald Young next up, is through to his third quarter-final appearance of the year, having made the last eight at the Brisbane and Sydney International events in Australia.
Tomic claimed the opening set in a canter on Thursday, having not faced a break point as he took control of the match.
Dolgopolov lifted his game in the second set but Tomic was up to the task, saving seven of eight break points faced as he improved to a 3-5 head-to-head against the world number 23.
"I played pretty good the first set," said Tomic. "After that was a rollercoaster, but I managed to stay in it and winning the second set was important ... I was down a break 4-1. I said to myself, 'It's only one break; stay in there and have a shot,' and it worked for me."
Young stands in the way of Tomic and a semi-final berth after the American defeated compatriot and qualifier Denis Kudla 7-5 6-3.
It was the pair's first meeting since this time last year, when Kudla got the better of Young in straight sets at the Memphis Open.
"I like to get a little revenge," Young said. "I like to play people the second time after I lose. It gives me a little more motivation."
Seeds Kevin Anderson and Steve Johnson both advanced to the quarters.
South African second seed Anderson accounted for big-serving Australian Sam Groth 6-3 6-2.
Anderson's straight-set wins earned a showdown against American sixth seed Johnson, who rallied to beat German Dustin Brown 4-6 7-5 7-6 (7-3).