Croatia's Marin Cilic beat fifth-seeded Grigor Dimitrov of Bulgaria 7-5, 7-5 today on a day dominated more by injury withdrawals in the women's draw than completed match results at the Brisbane International.
Fifth-seeded Angelique Kerber of Germany moved into the quarterfinals after Russian Anastasia Pavlyuchenkova retired with a left leg injury.
Kerber was leading 6-2, 4-3 against last year's tournament runner-up.
Pavlyuchenkova's withdrawal followed that of Wimbledon finalist Sabine Lisicki, who pulled out of her match earlier Wednesday against Swiss player Stefanie Voegele due to a gastrointestinal illness.
Maria Sharapova also got a walkover win when her scheduled second-round opponent, Australian teenager Ashleigh Barty, withdrew late Tuesday with an adductor injury.
Later Wednesday, top-seeded Roger Federer wasscheduled to play his first singles match at Brisbane - a second-rounder against Finnish veteran Jarkko Nieminen.
And the United States team of John Isner and Sloane Stephens was set to play France at the Hopman Cup at Perth.
In Auckland, New Zealand at the WTA's ASB Classic, former world No. 1 players Venus Williams and Ana Ivanovic moved closer to a semifinal meeting when they won second-round matches.
Williams overcame a rusty start to beat Yvonne Meusburger of Austria 4-6, 6-3, 6-2 while second-seeded Ivanovic defeated Sweden's Johanna Larsen 6-1, 6-1.
Rain briefly halted the first set of the Williams match at 1-1 and the American dropped serve when the match resumed after 15 minutes.
She claimed the break back but dropped serve again to lose the opening set in 41 minutes.
''I was in a hole early on because she was playing so well,'' Williams said. ''At the beginning of the year matches are much more intense than practice so sometimes you get a little niggly here and there. That's what I'm experiencing but the adrenaline of matches really helps.''
The injury jinx extended to next week's Sydney International, where organizers of the ATP-WTA tournament said Nicolas Almagro of Spain had withdrawn with a shoulder injury.
On Wednesday, former No. 1 Caroline Wozniacki trained for the Sydney International just hours after announcing that she and golfer Rory McIlroy were engaged to be married.
McIlroy apparently used the Sydney Harbour fireworks display as the backdrop for his proposal.
''Happy New Year everyone! I have a feeling it's going to be a great year!! My first victory of 2014 shesaidyes!!'' McIlroy tweeted.
Wozniacki, who withdrew from the Brisbane tournament after injuring her right shoulder in a training session, posted a photo of her diamond engagement ring.
''Happy New Year everyone! Rory and I started 2014 with a bang! ... I said YES,'' Wozniacki tweeted.