San Diego: Maria Sharapova has never been afraid of speaking her mind and the Russian freely admits that a desire to build on a successful start to her career is fuelled by the prospect of an ever-expanding bank account. "It's never enough. I always look for more," Sharapova said at the Acura Classic on Thursday. "Bring on the money." According to a recent survey in Sports Illustrated, the 19-year-old world number four is the world's highest-paid female athlete, earning an estimated $25.4 million a year. Sharapova is also ranked number four on the magazine's international top-20 list, behind Formula One driver Michael Schumacher, MotoGP rider Valentino Rossi and soccer star Ronaldinho. However, she has moved ahead of Real Madrid's David Beckham, baseball player Ichiro Suzuki and Swiss tennis player Roger Federer, who earns an estimated $22.1 million a year. Sharapova, who has endorsements from a string of multinational companies, says she will always find time for another major contract. "When I was working my way to the top of tennis, I didn't say I was number two, I said I wanted to be number one," she said. "There's not limit to how much money you can make." Sharapova has a single grand slam title to her name (Wimbledon 2004) but says she would happily trade all of her millions for another three grand slam titles, but not just because of the tennis glory. "Of course, because another three slam titles will bring a lot more than $25 million," she said. "They would be worth even more (than $100 million)." Sharapova said she was proud to be on the list, but would rather be known for what it took to get her there. "It's a cool fact, but I don't live my life by looking at these facts, how much (money) I have won," she said. "What tennis has brought me has been incredible. God gave me a talent, but it was up to me to play my part in it. "I don't believe in just god-given talent, you have to work for everything you earn and I think the combination has helped me." During her three-week layoff between Wimbledon and San Diego, Sharapova trained in Los Angeles and went to see US men's player Andy Roddick compete at the ATP tournament there. Sharapova would not deny a report in the US media that the pair were dating, but had no comment. "I don't discuss my private life," she said.