Memphis: Milos Raonic hammered a career-high 38 aces defeating Radek Stepanek 6-4, 6-7 (10/12), 7-6 (7/1) on Thursday to reach the quarter-finals of the ATP/WTA Memphis event.
After dropping a marathon second set tiebreaker, Canada's Raonic needed a tiebreaker in the third to oust the Czech star and post his sixth consecutive victory.
He will next face American qualifier Robert Kendrick for a spot in the semi-finals.
In other second round matches on Thursday, American Sam Querry beat Brian Dabul of Argentina 6-3, 7-6 (7/3) and Juan del Potro, of Argentina, easily beat Croatian Ivan Dodig 6-4, 6-4.
It was a quick turnaround for Raonic who beat second seeded Fernando Verdasco on Wednesday, upsetting the Spaniard for the second time in three days.
Raonic squandered four match points in the second-set tiebreaker but still held on to win in two hours and 32 minutes.
His 38 aces was the fifth most struck in a three-set match since the ATP began keeping those statistics in 1991.
On Sunday, Raonic defeated Verdasco 7-6, 7-6 in the ATP San Jose final, denying the Spaniard his second title in a row at the event while becoming Canada's first ATP singles winner in 16 years.
The 20-year-old became the youngest winner on the Tour since 19-year-old Marin Cilic won three years ago at the New Haven tournament.
Raonic has rocketed up the ATP rankings this year going from 156 in the world at the end of last year to 59th.
On the women's side of the draw Thursday, Russian Evgeniya Rodina, Czech Lucie Hradecka, Rebecca Marino of Canada and Magdalena Rybarikova all advanced to the semi-finals with straight-set victories.
Marino, the only seeded player remaining at No. 6, defeated American Coco Vandeweghe 6-1, 7-6 (8/6).