Maria Sharapova's Monday began with a wake-up call from her father, Yuri, who greeted her with, "Good morning, champion!" It was heartfelt notice of what the Women's Tennis Association's computers had just made official: Sharapova had ascended to the world No. 1 ranking.

At 18 years and four months, Sharapova is the fifth youngest to claim the top spot in women's tennis. She's also the first Russian woman to be ranked No. 1, and during a conference call with reporters she was positively giddy over having reached her lifelong goal at age 18.

"Now that you know you've achieved it, I just never have to prove anything to anyone," Sharapova said. "I don't think anyone expected me to win Wimbledon at 17, and no one expected me to be No. 1 at 18."

Sharapova supplants American Lindsay Davenport, who had held the top spot for 44 consecutive weeks, since Oct. 18, 2004, before being sidelined in late July by a back injury.

Sharapova captured the international spotlight by winning the 2004 Wimbledon title at age 17 and closing the year with the WTA Tour championship. Since then she has parlayed her on-court achievements into marketing millions, signing endorsement deals with Motorola, Canon, and TAG Heuer watches, among others.

As the world's No. 1, Sharapova can expect to be rewarded with the top seed for the U.S. Open later this week.

Davenport drops to second in the rankings. Amelie Mauresmo of France remains third, while Kim Clijsters of Belgium vaulted from eighth to fourth after winning her sixth title of the year on Sunday in Toronto. Sisters Serena and Venus Williams round out the American top 10 contingent, ranked eighth and 10th, respectively.

-- Liz Clarke