Naomi Osaka benefitted from the second round defeat of former number one Ashleigh Barty and the failure of Karolina Pliskova to reach the semis in Toronto.
Roger Federer is the oldest man to book a last-16 place since Tunisian-born Italian Nicola Pietrangeli, a two-time champion, at the age of 38 in 1972.
Serena Williams heads into this year's French Open with questions surrounding her fitness while Naomi Osaka needs to rediscover her best form to solidify her position at the top of the women's game.
Ashleigh Barty will rise from 11th to number nine in the world rankings and become the first Australian woman since Sam Stosur in June 2013 to crack the top 10.
Serena Williams' bid for her 24th Grand Slam title was brought to a shuddering halt by Karolina Pliskova.
Serena Williams is gunning to match Margaret Court's record of singles majors and claim an eighth Australian Open crown.
Former world number one Karolina Pliskova booked her spot in the semi-finals for the second straight year having also beaten Wozniacki earlier in the tournament.
Karolina Pliskova needed just 63 minutes to complete a clinical 6-4, 6-4 victory over Naomi Osaka in Tokyo.
Six-time champion Serena Williams shook off a sluggish start to power past eighth-seeded Karolina Pliskova 6-4, 6-3 on Tuesday and into the US Open semi-finals.
Maria Sharapova's last win over Serena Williams came at the 2004 WTA Tour Championships -- before even the birth of Twitter and YouTube.
Maria Sharapova will return to the showpiece Court Philippe Chatrier for the first time while Rafael Nadal defends his 15-0 record over Richard Gasquet.
Karolina Pliskova rallied from a set down to beat fellow Czech and 20th seed Barbora Strycova 6-7 (5/7), 6-3, 6-2 and make the Australian Open quarter-finals.
World number one Rafael Nadal notched up his 50th win at the US Open on Monday to reach the quarter-finals for the seventh time.
Rafael Nadal and Roger Federer won their third round matches to move closer to a blockbuster semi-final clash at the US Open.
Switzerland's Federer will be seeking his 20th Grand Slam title and his sixth in New York.
Australia's Nick Kyrgios humbled new world number one Rafael Nadal 6-2, 7-5 to reach Cincinnati Masters semi-finals on Friday.
Five tennis players have a chance to grab the world No 1 ranking at this week's Cincinnati Open.
Roger Federer climbed to No 3 in the latest ATP singles rankings while Karolina Pliskova topped the WTA charts despite never having won a Major.