Melbourne - Chinese qualifier Zhang Shuai maintained her dream Australian Open run Monday as she battled past injured and tearful 15th seed Madison Keys and into a quarter-final against British hope Johanna Konta.
Zhang had lost all 14 of her previous Grand Slam matches before this year's tournament but she has now won four in a row after beating Keys 3-6, 6-3, 6-3 as the American struggled with an upper left leg injury.
Her reward is a showdown with the unseeded Konta, who spent more than three hours on court to grind down Russian 21st seed Ekaterina Makarova, a semi-finalist last year, 4-6, 6-4, 8-6.
But it was a devastating finale for Keys, who needed treatment on her leg which hampered her movement. She gamely continued but was clearly in pain as she wept freely on court.
"Bad luck Madison. She was injured and I'm very lucky today," said Zhang.
"It was so difficult to concentrate because I could see she was in pain."
"But it's so exciting for me," she added, on her amazing achievement in reaching the quarter-final.
The 27-year-old, who nearly retired last year, has now accounted for world number two Simona Halep, 33rd ranked Frenchwoman Alize Cornet, 51st ranked Varvara Lepchenko and Keys.
Zhang first came to prominence in 2009 when she became the lowest ranked player to defeat a reigning world number one -- Dinara Safina at the China Open, and she was once ranked 30th in the world.
But her serial failure at Grand Slams and a horror 2015 in which she fell eight times in the first round and six times in qualifying convinced her it was time to call it quits.
Her team told her to give it one more shot at Melbourne Park this year, and she now has a chance to make the semi-finals.
Keys, one of the biggest hitters in the game and a semi-finalist last year, signalled her intentions from the word go, racing to an early break.
Zhang got off the mark by holding serve with a crosscourt forehand to trail 1-2.
It went with serve until the ninth game when Zhang saved three set points but could do nothing about the fourth, and Keys punched the air as she took the set -- the first the Chinese star has lost all tournament.
But Zhang refused to give in and she stunned Keys by breaking her for a 2-1 lead, at which point the American called for a medical timeout and left the court, returning with strapping on her upper left thigh.
Zhang held serve to love with Keys clearly struggling with the injury. She worked three break points on the next Zhang serve but with her movement hampered, she was unable to run down the wide balls.
Keys battled hard and saved two break points on her next serve but the discomfort was clear and a double fault when 3-5 down handed Zhang the set and a way back into the match.
She soldiered through the third set but was clearly in pain and the tears came at 2-3 down. It ultimately proved too much and Zhang raced to the win to continue her remarkable run, as Keys left the court sobbing.