Riske created one of the biggest shocks of the tournament with her 3-6, 6-2, 6-3 victory over French Open champion Barty who was on the sort of run that made losing to a player of the American's lowly 55th ranking appear almost impossible.
In knocking World No 1 Ashleigh Barty out of Wimbledon, Alison Riske showed that when your dad is a former secret service agent and FBI investigator, you learn how to turn the screw on even the most intimidating opponents.
Riske created one of the biggest shocks of the tournament with her 3-6, 6-2, 6-3 victory over French Open champion Barty who was on the sort of run that made losing to a player of the American's lowly 55th ranking appear almost impossible.
Yet Riske, who once described herself as "100 percent paranoid" and in a state of fear brought about by her dad's line of work, set about ending Barty's 15-match winning streak without a hint of intimidation.
"I couldn't begin to say what it means to me. To have overcome the matches the way I have is what I'm most excited about," she said.
"Getting to the quarter-finals is amazing but what's most exciting for me is the way I've been fighting."
She lost the first set but dug in for a trench battle, out-slugging the Australian to take the next two and set up a potential last-eight clash with seven-times champion Serena Williams.
On paper, Riske seemed to have little chance of causing an upset. At 29, she had never reached a Grand Slam quarter-final and had spent over four hours more on court than Barty in the first week.
Yet her three previous matches, which all went the distance, told of a fighting spirit and battle-hardened endurance that would not give an inch if she could drag Barty into a dogfight.
After Barty won the first set, the 21st in a row she had taken since her French Open semi-final, it seemed she might continue a run at Wimbledon that had seen her glide through her opening three matches in three hours, losing only 12 games.
Yet Riske broke in the fourth game of the second set and then again in the eighth as Barty struggled to execute in the face of relentless pressure from the American.
There was little to separate the players in the third set until the eighth game when Riske hit a ferocious backhand winner to set up a break point and followed that with another off the other flank to bring the finish line into sight.
She brought up match-point on her serve and a fierce contest was brought to a halt when Barty sent a backhand wide, leaving Riske to relax and enjoy the moment.
That is not an emotion she has always been able to experience.
Riske, who once jokingly described her dad as "Robert De Niro 100%" after the character in the 'Meet the Parents' films, said she grew up paranoid about everything.
Going out, she said involved "always looking left and right... Or, you're in a crowded place, be alert. Where's the closest exit sign if you need to escape?"
She seems in no hurry to exit Wimbledon and could face Williams in the next round, if the 23-times Grand Slam singles champion beats Carla Suarez Navarro on Monday.
