"I believe in my game," Sharapova said. "I think that's one of the reasons I'm sitting here with my fourth one and winning Roland Garros, because I always believed I could be a better player."
Second-seeded Sharapova, who was guaranteed of moving to No. 1 in the rankings regardless of the result, jumped to a quick 4-0 lead against the 21st-seeded Errani, who was in her first Grand Slam final.
But Errani battled back on a cool, blustery day in Paris, turning what had the makings of a blowout into an 89-minute endurance contest, filled with long rallies that forced Sharapova to find another gear. Eventually, Sharapova's bigger serve and bigger groundstrokes wore down the 5-foot-4½ Errani.
"She won many points with her serve or in the first two or three shots," Errani said. "It was difficult. I couldn't play long points like I wanted to play."
When Errani netted a short backhand on the third match point, Sharapova dropped gingerly to the clay to start the celebration, then reached back and looked heavenward a long, hard road back to the top finally capped with the only major title that had eluded her.
Sharapova won the trophy at Roland Garros about three years after dropping as low as 126th in the rankings after shoulder surgery that threatened her career. She rededicated herself to the game and made a special effort to improve on red clay, the surface on which she moved to 16-0 this year.
She did it knowing it wasn't really necessary. She's a millionaire many times over, her endorsement cachet full as comfortable on the red carpet as she now is on the red clay.
"I've had so many outs, and I could've said I don't need this," she said. "I could've said, 'I've got the money, I've got the fame, I've got the career victories and Grand Slams.' But when your love for the game is bigger than those things, that's when you continue to get up."
She added this year's French Open title to championships at Wimbledon in 2004, the U.S. Open in 2006 and the Australian Open in 2008 to become only the 10th woman to win all four major tournaments, joining players such as Chris Evert, Martina Navratilova, Serena Williams and Billie Jean King.
It was Sharapova's 27th overall career title. She'll be back at No. 1 in the WTA rankings Monday for the first time since June 2008, though this win reminded her of a scene a few years before that.
Back in 2004, Sharapova was 17, just becoming a name on the tennis scene when she swept into Roland Garros and made a surprise trip to the quarterfinals. A preview of things to come: A month later, she won Wimbledon and everyone knew her name.
"I thought when I won Wimbledon at 17, that would be the most treasured moment in my career," she said. "But when I fell down on my knees today, I realized this is extremely special, even more so."
The lopsided score in the final wasn't all that unexpected, given the size, experience and power advantage Sharapova brought to her first meeting with Errani. But really, the score didn't tell the whole story.
Errani, who won the doubles title Friday and will move to the top 10 in singles for the first time Monday, struck a victory for any athlete, from the pros to the playground, who has ever looked up at an opponent towering over them by a foot and said, "Hey, maybe I can do this."
Despite spinning serves in at 70 to 80 mph, while Sharapova was topping out in the 115 mph range, Errani played Sharapova toe-to-toe for the better part of the hour and a half, especially after she overcame the jitters in the shaky opening games.
Eventually, Sharapova's power game won out but Errani fought to the bitter end showing the savvy to hit two drop shots that won points in the final game, each of them sending Sharapova scrambling toward the net, only to arrive a split second late.
Still, Sharapova finished the match with 25 winners from the baseline compared to four for Errani, while committing 29 unforced errors to 11 for her opponent. Sharapova also led in aces, 6-0, including one that set up the third and final match point the one match point that had been missing in an otherwise stellar career.
"It's a long journey," she said. "It started from a very young age, and it's not over yet. I'm not sitting here and saying I'm done because I'm far from it. I have a lot more in me to achieve."
French Open women's champions
2012 • Maria Sharapova
2011 • Li Na
2010 • Francesca Schiavone
2009 • Svetlana Kuznetsova
2008 • Ana Ivanovic
2007 • Justine Henin
2006 • Justine Henin-Hardenne
2005 • Justine Henin-Hardenne
2004 • Anastasia Myskina
2003 • Justine Henin-Hardenne
Women's career Grand Slams
Margaret Smith Court (24) • Australian (1960-66, 1969-71, 1973), French (1962, 1964, 1969-70, 1973), Wimbledon (1963, 1965, 1970), U.S. (1962, 1965, 1969-70, 1973)
Steffi Graf (22) • Australian (1988-90, 1994), French (1987-88, 1993, 1995-96, 1999), Wimbledon (1988-89, 1991-93, 1995-96), U.S. (1988-89, 1993, 1995-96)
Martina Navratilova (18) • Australian (1981, 1983, 1985), French (1982, 84), Wimbledon (1978-79, 1982-87, 1990), U.S. (1983-84, 1986-87)
Chris Evert (18) • Australian (1982, 1984), French (1974-75, 1979-80, 1983, 1985-86), Wimbledon (1974, 1976, 1981), U.S. (1975-78, 1980, 1982)
Billie Jean King (12) • Australian (1968), French (1972), Wimbledon (1966-68, 1972-73, 1975), U.S. (1967, 1971-72, 1974)
Serena Williams (12) • Australian (2003, 2005, 2007, 2009-10), French (2002), Wimbledon (2002-03, 2009), U.S. (1999, 2002, 2008)
Maureen Connolly (9) • Australian (1953), French (1953-54), Wimbledon (1952-54), U.S. (1951-53)
Doris Hart (6) • Australian (1949), French (1950, 1952), Wimbledon (1951), U.S. (1954-55)
Shirley Fry (4) • Australian (1957), French (1951), Wimbledon (1956), U.S. (1956)
Maria Sharapova (4) • Australian (2008), French (2012), Wimbledon (2004), U.S. Open (2006)
P Novak Djokovic vs. Rafael Nadal Sunday, 7 a.m.
TV • Ch. 5