Highlights: Australian Open day 10

MELBOURNE (Reuters) - Serena Williams blew a 5-1 final set lead against seventh seed Karolina Pliskova in the quarter-finals of the Australian Open on Wednesday, squandering four match points as she was beaten 6-4 4-6 7-5. Pliskova stunned a packed Rod Laver Arena with a fightback for the ages as she rallied from the brink of defeat to deny Williams the chance to keep alive her hopes of winning a record-equaling 24th Grand Slam title. Williams rolled her ankle when serving for the match at 5-1, but denied that the injury had thrown her off her stride. "It was nothing to do with my ankle," the 16th seed said. "Obviously I made some mistakes but she played really well. She was hitting the lines and went crazy. She played unbelievable on match points." Next up for Pliskova is a semi-final meeting with Japan's Naomi Osaka on Thursday, while her fellow Czech Petra Kvitova faces unseeded American Danielle Collins in the other semi-final. Pliskova, Kvitova and Osaka are locked in a three-way battle to wrest the world number one spot from Simona Halep, and Pliskova will emerge as the top-ranked woman in the world if she wins her first career grand slam title in Melbourne. In the men's draw, six-times champion Novak Djokovic reached the last four for the seventh time in his career after his quarter-final opponent, Japanese dynamo Kei Nishikori, retired with an injury while trailing 6-1 4-1. Djokovic, who has gone on to win the title each time he has reached the semi-finals in the past, faces Frenchman Lucas Pouille on Friday. Second seed Rafa Nadal and Greek youngster Stefanos Tsitsipas meet in the other men's semi-final on Thursday. Highlights of Wednesday's 10th day of the Australian Open, the first Grand Slam tournament of the year (all times GMT): 0944 NISHIKORI RETIRES FROM SEMI-FINAL Novak Djokovic reached the semi-finals after Kei Nishikori retired injured while trailing 6-1 4-1. Japan's Nishikori, who has spent close to 14 hours on court before the match, called for the trainer and received treatment for a right thigh problem after the first set before he was forced to retire. 0747 POUILLE REACHES MAIDEN SLAM SEMI-FINAL Lucas Pouille defeated big-serving Canadian Milos Raonic 7-6(4) 6-3 6-7(2) 6-4 in a little over three hours to reach the semi-finals of a Grand Slam for the first time in his career. Pouille trailed 2-5 but came back to clinch the first set in the tiebreak, before racing through the next. Raonic claimed the third set to give himself hope, but Frenchman Pouille switched gears in the next to seal the win on his third match point. 0421 PLISKOVA ENDS WILLIAMS' RUN Former world number one Karolina Pliskova overcame Serena Williams 6-4 4-6 7-5 to storm into the semi-finals where she takes on U.S. Open champion Naomi Osaka. The Czech looked strong in the first set but dropped the next as Williams got into her groove. Williams raced to a 5-1 lead in the decider but appeared to sustain an ankle injury, allowing Pliskova to fight back and prevail in two hours and 10 minutes. Defeat ended Williams' quest to claim a record-equalling 24th Grand Slam crown. 0233 OSAKA PLEASED WITH PERFORMANCE AGAINST SVITOLINA Naomi Osaka said keeping her temper in check had helped her seal a comfortable 6-4 6-1 win over sixth seed Elina Svitolina to reach the Australian Open semi-finals. "For me, today, I had one goal - it was to try as hard as I can and not get angry. I didn't do that well in the past two rounds, but I played well today," the Japanese said. "I tried to be consistent, or as consistent as I can be. She is really good but unfortunately she was injured. But playing against her injured was really tough." (Reporting by Shrivathsa Sridhar and Hardik Vyas in Bengaluru; Editing by Peter Rutherford and Simon Jennings)