Check out some of the headlines and results from the top tournaments around the world that you may have missed while you were sleeping.
Yet another WTA Top 10 early exit
The season is just a few days old and we've already seen almost all of the WTA's Top 10 players withdraw or retire from matches at their Australian Open tune-ups. World No. 3 Garbine Muguruza kept the streak going on Wednesday, retiring with a left foot injury down 7–6, 1–0 to Varvara Lepchenko in Brisbane. It was later confirmed that the injury is related to ongoing issues with plantar fasciitis in her foot.
"I'm not really worried because I felt it a lot, so it's really necessary to do a lot of treatment and to keep it not like getting worse," she said after the match. "Last year I felt it almost during the whole season...I felt it during the preseason a little bit, but especially here last days playing points, running more, more, more."
After No. 1-seed Simona Halep's withdrawal from the tournament with a nagging Achilles injury and No. 2-seed Maria Sharapova's decision to pull out because of a forearm injury, the highest remaining seeds are No. 4 Angelique Kerber, who beat Madison Brengle, and No. 6 Carla Suarez Navarro who topped Sam Stosur on Tuesday. The draw is wide open for Kerber, Suarez Navarro, Victoria Azarenka and Andrea Petkovic. Thursday's quarterfinals matchups are set: Azarenka-Vinci, Petkovic-Crawford, Kerber-Pavlyuchenkova and Suarez Navarro-Lepchenko.
Upsets rule in Auckland
No. 3 Caroline Wozniacki and No. 5 Sloane Stephens are the only two remaining seeds at the ASB Classic in Auckland, which has been full of drama in the opening rounds. Defending champion and top seed Venus Williams lost in her opener to Daria Kasatkina and Britain's Naomi Broady knocked out second-seeded Ivanovic. Tamira Paszek also scored an upset on Wednesday, beating No. 4-seed Svetlana Kuznetsova. Kasatkina was unable to replicate her level in the first round and lost to Japan's Nao Hibino, but Broady battled in a tough three-setter—saving two match points and rallying from 5–2 down in the second set and 5–1 down in the final set—to defeat Jelena Ostapenko and advance to a quarterfinal matchup against Stephens.
But Broady’s win on Wednesday did not come without controversy. In the second set after Broady hit a winner, Ostapenko’s racket flew out of her hand, bounced off the court and against the back wall, almost hitting a ball boy. The umpire and ball boy discussed the incident and then Ostapenko was giving a code violation—but Broady was clearly upset and the tension continued to build into the final set.
Caroline Wozniacki also advanced on Wednesday, beating Christina McHale 6–0, 6–2.
Djokovic continues to cruise in Doha
The World No. 1 is now 2–0 on the season for 2016 after two commanding wins at the Qatar Exxon Mobil Open in Doha. On Wednesday, Djokovic needed just 69 minutes to take down Fernando Verdasco and will play Leonardo Mayer in the quarterfinals. Last year, Djokovic fell in the quarterfinals in three sets to Croatia's Ivo Karlovic, 6–7 (2) 7–6 (6), 6–4.
Rafael Nadal also continued his run in Doha with a 6–3, 6–2 win over Robin Haase in 65 minutes on Wednesday
Serena withdraws from Hopman Cup as Australia Green surges
After cutting her first match of the 2016 season short on Tuesday, Serena Williams withdrew completely from Hopman Cup on Wednesday due to a left knee injury. Vicky Duval will take her spot in the tournament.
"I just have some inflammation that's been going away very slowly," she said after withdrawing on Tuesday. "It's going away, but just needs a little more time. I've been training really hard during the off-season. Really pushing myself beyond the limits. I just think a day off or two will make a world of difference."
In Great Britain's round robin tie against Australia Green, Nick Kyrgios pulled off the upset over Andy Murray, beating him 6–4, 7–6 (5) after Murray failed to take set point at 5–4. But Heather Watson leveled the score for her team with a thrilling 6–7 (2), 6–2, 7–5 win over Daria Gavrilova. In the mixed doubles decider, Murray and Watson came back to win the second 7–6 to force a third set, but just missed out in the deciding tiebreak. Kyrgios and Gavrilova secured the win for Australia Green just after midnight local time in Perth.
Sabine Lisicki and 18-year-old Alexander Zverev also got their first win together in mixed doubles on Wednesday, beating France's Caroline Garcia and Kenny De Schepper 6–4, 6–7(6), 10-6 in another entertaining match.
Other notable results
Chennai Open: Stan Wawrinka d. Andrey Rublev 6–3, 6–2; Borna Coric d. Austin Krajicek 6–2, 7–5; Roberto Bautista Agut d. John Millman 6–4, 6–1; Guillermo Garcia-Lopez d. Ante Pavic 7–6, 6–1
Shenzhen Open: Eugenie Bouchard d. Nicole Gibbs 6–4, 6–2; Anett Kontaveit d. Saisai Zheng 6–1, 6–2; Agnieszka Radwanska d. Shuai Zhang 6–1, 7–5; Katerina Siniakova d. Zarina Diyas 6–0, 6–4