Serena: 'We all know who No. 1 is'
"We all know who the real number one is," Williams told a news conference at the Italian Open on Monday. "Quite frankly, I'm the best in the world."
Second-ranked Williams, who will face Swiss Patty Schnyder in her opening match in Rome, felt she could back up her claim because she owns 10 Grand Slam singles titles while Safina's tally stands at zero.
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Asked which opponent she feared most, the American quipped: "Probably myself. I always beat myself."
Safina, the younger sister of former men's No. 1 Marat Safin, said time would tell if her rival was right.
"She can say this because she won many more Grand Slams than me," the 23-year-old said.
"But she's also older than me so she has more experience. So let's see when I'm her age how many titles I have and then we can say," added Safina, who has contested 10 finals over the past 12 months, winning four titles.
"It's not luck. Nobody gave it to me. I played two Grand Slam finals and last year I won four titles. This didn't come out of sky."
The 27-year-old, who has already dabbled in fashion designing and acting, said she was thinking about expanding her off-court interests.
"I've been writing, but I haven't been writing. In my mind I've been saying I want to write, but I haven't actually physically picked up a pencil and started writing," the U.S. Open and Australian Open champion said.
"So that is my next challenge, to actually to sit down and do it. No [not my life story]. A screenplay. Nothing is impossible."