Maria Sharapova has admitted that Germany's Sabine Lisicki will provide an "extremely difficult" challenge when the two meet in the third round of the Olympic singles later today.
Lisicki knocked the Russian third seed out in the last 16 of the Wimbledon Championships last month.
When asked if the German would pose a hard test, Sharapova told reporters: "Yeah, an extremely difficult opponent. I lost to her just a few weeks ago here at Wimbledon. She played at a really high level. I hope I'll change a few things around in order to change the result."
The French Open winner defeated Great Britain's Laura Robson in straight sets in their second-round encounter on Tuesday.
