Serena's strength is key to her success, says beaten Clijsters

Supremacy is a constant topic when Serena Williams is in the interview room. Having reached the final of the Nasdaq-100 Open here without playing well, the world No 1 said: "If I'm playing my best tennis, I don't think anyone right now can beat me."

Kim Clijsters, figuratively kicking herself for not being able to take advantage after catching the defending champion on an off day in their semi-final on Thursday – not to mention being reeled in after leading her 5-1 in the final set in the Australian Open semi-finals – was not inclined to disagree.

"I'm sure Serena hits the ball even harder then [her sister] Venus," the Belgian world No 3 said. "She serves better than Venus. She moves unbelievably well. So if she leaves the unforced errors out, I don't see how anyone else could beat her. But in a tennis match, it doesn't always go your way.

"It happened at the WTA Tour Championships in Los Angeles. She wasn't playing her best tennis. I was just fighting for every ball and made her play her shots. She was missing a few. Those are the chances you have to grab. Today, I just didn't get any of those."

Clijsters, who defeated Serena in the final of the WTA Tour Championship last November, could only muster six winners in losing to her here, 6-4, 6-2. "I played probably the best mover in the game," she said. "I don't think that's very surprising."

The manner of Clijsters' defeat at the Australian Open undoubtedly left a scar. Her performance here on Thursday was disappointing rather than disastrous. "After the match is over, it's over," she said. "Of course, you think back on it a little bit and keep things in mind for the next time you play them. But I'm not going to say: 'Why didn't I do this? Why didn't I do that?' It's too late anyway." Yesterday she pulled out of the doubles because of an upset stomach.

Asked what she could do to improve her chances, Clijsters said: "I can always be fitter or stronger, but then my movement will go off or I'll get slower if I want to be stronger. And if I want to be fitter and lose weight, then I probably won't be able to hit the ball as hard. I think Serena is a head taller than me. She's a lot stronger than me. Those things make a difference."

With strength and fitness now the dominant features in the women's game, so the element of hit-or-miss has increased. "Because we hit the ball so hard and go for so many shots," Clijsters said, "I think you'll see a lot more unforced errors than a few years ago. You'll see some amazing points, some amazing winners from maybe a metre behind the baseline. But you'll see unforced errors as well.

"I've always played risky tennis. If you look at the players who are in the top 10 now, they all hit the ball very hard and they all make some mistakes because they take so many risks."

Clijsters intends to take a few weeks' R & R to recharge her batteries for the European clay-court season leading up to the French Open at the end of May. "I feel pretty tired, mentally and in my body," she said. "I didn't play that many tournaments, but I did well in all of them, singles and doubles. I need some time off. We are due to play Fed Cup in about a month, so I won't be doing anything for the next two or three weeks."

The 19-year-old from Bilzen plans to spend time with her family and her three dogs, a Saint Bernard, a Newfoundlander, and the latest addition, a British Bulldog puppy named Beauty. "I speak to them on the phone, that's how hard I miss them," she said.

Beauty, a gift from one of Clijsters' sponsors, was presented to her in Belgium after she played an exhibition match against her compatriot, Justine Henin-Hardenne. "Because I'm building a house in Belgium, the sponsor said they wanted me to be safe, so they were giving me an alarm system," Clijsters said. "The lady from my sponsors was holding a big basket with a big bow on top. I was expecting something electrical to be in the basket. All of a sudden, I see this little head pop up."

Asked what her boyfriend, Lleyton Hewitt, the men's world No 1, thought of the dogs, Clijsters said: "He's actually allergic to dogs, so that's not such a great thing. He's OK. He loves the bulldog. She came to the tournament in Antwerp. She was sharing the room with us. She was really good."

Albert Costa, the French Open champion, advanced to the semi-finals of the men's singles yesterday, defeating Roger Federer, the Swiss fourth seed, 7-6, 4-6, 7-6. The conclusion of the match had been delayed overnight because of rain with Costa leading 6-5 in the final set.

Australia will monitor world developments and security issues before deciding whether their Fed Cup team will travel to Spain for their first-round match in Tarragona next month.