Caroline Wozniacki's hopes of a first Wimbledon title are over for another year after she departed in the second round, but Karolina Pliskova and the Williams sisters are still in the mix.

World number two Wozniacki ended her wait for a grand slam crown at the Australian Open, but she fell well short at the All England Club on Wednesday, losing 6-4 1-6 7-5 to Ekaterina Makarova.

Pliskova, the seventh seed, battled past Victoria Azarenka in straight sets, while both Serena and Venus Williams also booked their places in the third round.

Madison Keys also progressed, beating Luksika Kumkhum in straight sets, along with Julia Goerges, but 2012 finalist Agnieszka Radwanska was knocked out by Lucie Safarova.

WOZNIACKI BUGGED BY LOSS

Wozniacki offered up few excuses for her defeat, despite complaining to the chair umpire as a swarm of flying ants descended on the court, her pleas for assistance greeted with bug spray.

"I don't think it had any impact, but it was definitely a first for me," she said of the insect invasion.

And the Dane was a little spiky when asked what might have instead been to blame, insisting her maiden grand slam win at the Australian Open should not mean she is automatically a contender in SW19.

"I don't understand what one has to do with the other," Wozniacki replied. "I lost today. It's obviously not the way I wanted the day to go."

PLISKOVA BREAKS NEW GROUND

Former world number one Pliskova had never previously reached the third round at Wimbledon, despite featuring in the latter stages of the other grand slams.

However, she put that record to bed on Wednesday, setting up a clash with Mihaela Buzarnescu, who ended the run of Brit Katie Swan with a resounding 6-3 6-0 triumph.

Asked to explain her previous struggles, Pliskova replied: "I don't know, but I'm happy that it has happened. For me, the past doesn't matter. The only time is now.

"This year I tried to not put that much pressure on myself because last year I think I put too much."

WILLIAMS SISTERS WIN AGAIN

Both Serena and Venus Williams remain in the draw after contrasting triumphs on Wednesday at Wimbledon.

Serena was comfortable as she defeated Viktoriya Tomova 6-1 6-4, but ninth seed Venus was given a scare as she battled back from a set down to beat Alexandra Dulgheru.

Yet Venus was not so pleased about the familiar line of questioning on eight-time men's champion Roger Federer afterwards.

When asked to evaluate Federer's form so far at this year's tournament, she answered: "I don't really watch tennis. I watch my match and that's all. I'm sure he plays amazing, though."

MEANWHILE...

Eugenie Bouchard, the 2014 finalist, was preparing for her own second-round match on Wednesday, but she was distracted on her drive in to practice.

Although the Canadian has no need for Wimbledon tickets as she competes in the main draw, she announced her desire to one day join the thousands in 'The Queue', the renowned line of spectators waiting hopefully to get in each day.

"Serious respect for your dedication to tennis. Thank you," Bouchard said in a message to those patient fans on Twitter.