World number ones Roger Federer and Amelie Mauresmo face potentially tricky Czech opponents in the fourth round of the French Open on Sunday.
Federer will be on high alert when he meets Tomas Berdych, who unexpectedly halted the Swiss maestro's Olympic gold medal charge at the 2004 Athens Games.
"He's a tough opponent...dangerous one," acknowledged Federer.
"Serves well. Can play good from the baseline. Has enough power to hit winners on every shot so tough match for me."
While seven-times Grand Slam champion Federer has set his sights on winning the only major crown missing from his collection, Mauresmo appears to have buried the demons that plagued her 11 previous visits to Roland Garros.
The local favourite will take on 16th seed Nicole Vaidisova as she bids to reach the quarter-finals here for only the third time.
After achieving her long-overdue grand slam breakthrough at the Australian Open, the Frenchwoman feels she is finally ready to live up to expectation on home territory.
"Over the past few months, I have changed the way in which I envision matches. I'm more relaxed," said the top seed.
"The level of my tennis has improved as compared to the past. Obviously, that makes me feel better on court. I have fun but I'm also concentrated on what I need to do."
FEARSOME SERVE
In the men's field, Spanish seventh seed Tommy Robredo faces the task of blunting Mario Ancic's fearsome serve if he wants to keep his potential date with Federer in the last eight.
Argentine Gaston Gaudio has kept a low profile in Paris despite being the 2004 champion. His next test will be against sixth seed Nikolay Davydenko.
Seven other Grand Slam winners will also be in action on Sunday when all eight last-16 matches will be contested in the women's draw.
Defending champion Justine Henin-Hardenne will face 2004 winner Anastasia Myskina, while Australian Open victor Kim Clijsters should fancy her chances against Slovakian Daniela Hantuchova.
Fourth seed Maria Sharapova can expect a tough outing in the all-Russian duel against Dinara Safina.
"I'm really looking forward to stepping up. I'm sure it's only going to get tougher from here," said 2004 Wimbledon champion Sharapova.
Wimbledon holder Venus Williams will want to extend her perfect 7-0 record against Patty Schnyder, while 2004 U.S Open winner Svetlana Kuznetsova will face Italian ninth seed Francesca Schiavone.
