Petra Kvitova: 'It will be tough to beat Serena Williams'

Former Wimbledon champion Petra Kvitova has admitted that the leading players in the women's game will need to be at their best to have a chance of defeating Serena Williams.

Williams has won Wimbledon on five occasions and is currently on a 31-match unbeaten streak, and Kvitova knows that it will be tough to deny the 31-year-old her sixth crown.

The 23-year-old told Reuters: "I think that the players have to be at 100%, and to play really, really well.

"Serena sometimes doesn't have a great day but she's still able to beat the other players."

Kvitova won Wimbledon in 2011, defeating Maria Sharapova in the final.