Zhang reaches Australian Open quarterfinals with merciless win over Keys

Australian Open surprise packet Zhang Shuai of China has shown no mercy to injury-ravaged American Madison Keys, recovering from a set down to progress to the quarterfinals.

The 27-year-old qualifier was up against it in her fourth-round match - her seventh overall this tournament - after falling behind to Keys.

But cheered on by a strong and noisy Chinese following on Rod Laver Arena, Zhang fought back winning the next two sets to post a 3-6, 6-3, 6-3 victory.

Zhang, who before this year's Australian Open had lost all 14 of her previous first-round matches in Grand Slam events, incredibly now finds herself in the last eight of the tournament.

She will meet Britain's Johanna Konta, another unseeded player, for a chance to feature in the final four of the 2016 Australian Open.

Zhang, who became the last player in the women's draw to book a place in quarters, said she found it very difficult to finish off Keys, who played through tears of pain in the final set after suffering a leg injury.

"It's so tough to play against someone (injured) because ... I saw her feel more pain," Zhang told reporters on Monday night.

"Maybe (for) two points you're feeling like (they) cannot play, and then next three balls, pong, pong, pong, make two aces (and) one winner.

"So, so tough. You don't know what's (going to) happen."

Zhang, who last week revealed she considered retirement at the back-end of a disheartening 2015 campaign, said she was no longer feeling any pressure, despite only being three wins away from winning a fairytale first Grand Slam.

"(I'm feeling) Less pressure because I think the big pressure (came in the) first round," she said.

"I'm so lucky (to) play against the second seed (Simona Halep).

"So for me no more pressure." Endit