PARIS -- What started out as a stroll became quite a struggle for Serena Williams.
After going up by a set and two breaks in the French Open final, she double-faulted away that lead. Then, suddenly, she trailed in the third set.
As the tension thickened, Williams was warned by the chair umpire for an audible obscenity. She even felt the need to hit one shot left-handed.
Ah, but when Williams plays her best, no one is better. Putting aside a lingering illness, a mid-match lull and a feisty opponent, Williams won her third title at Roland Garros and 20th Grand Slam singles trophy by beating 13th-seeded Lucie Safarova of the Czech Republic 6-3, 6-7 (2), 6-2 on Saturday.
The No. 1-seeded Williams took the last six games and added to her 2002 and 2013 championships on the French Open's red clay. Those go alongside six each from the U.S. Open and Australian Open, and five from Wimbledon.
"When I was a little girl, in California, my father and my mother wanted me to play tennis. And now I'm here, with 20 Grand Slam titles," Williams said in French. "This is very special for me. I haven't always played very well here, but I'm really happy to win the 20th here."
Only two women in the century-plus history of Grand Slam tennis have won more major titles than the 33-year-old American: Margaret Smith Court with 24, and Steffi Graf with 22.
Williams also stretched her Grand Slam winning streak to 21 matches, following titles at the U.S. Open last September and Australian Open in January. She is the first woman since Jennifer Capriati in 2001 to win the Australian Open and French Open back-to-back and will head to the grass courts of Wimbledon this month with a chance to extend a bid to do just about the only thing she hasn't accomplished: win a calendar-year Grand Slam.
This one, though, did not come easily for Williams, who skipped practice Friday because she was sick, preferring to rest in her Paris apartment.
Owner of the most feared serve in women's tennis, she double-faulted 11 times, part of 42 total unforced errors, 25 more than Safarova. And Williams was down 2-0 in the third set.
But she kept aiming shots for lines and getting them to go where she wanted, improving to 32-1 in 2015, including 12-0 in three-setters.
When Saturday's match was over, Williams dropped her racket, threw her head back and lifted her arms into a "V." In the stands, her coach, Patrick Mouratoglou, stood and raised his hands. He held aloft two fingers on his right and made a fist with his left, to symbolize "20."
And to think: Four times over the past two weeks, Williams dropped the opening set before coming back to win, including in Thursday's semifinals, when she was lethargic and, Mouratoglou would say afterward, bothered by the flu, a fever and difficulty breathing.
So the most meaningful question leading into the final against Safarova, a 28-year-old lefty with a whip-like forehand who was making her Slam final debut in her 40th major appearance, was this: How healthy would Williams be?
She began providing answers from the get-go on a sunny afternoon.
Williams closed the first game with a 120 mph (194 kph) ace. As if to prove her timing on returns was just fine, too, she pounded a 104 mph (167 kph) serve with a cross-court forehand so powerful and precise that Safarova didn't bother to step toward the ball, watching the winner sail by for a break that made it 3-1 on the way to an simple first set.
It was 4-1 for Williams in the second, seemingly all but over, when she began to falter, and a dull match came to life.
Coughing between points, Williams double-faulted twice in a row to get broken for the first time, then double-faulted again to make it 4-all. When Safarova, growing ever more confident, held moments later, she had taken four consecutive games.
Safarova stood strong in the tiebreaker and at the outset of the third set, displaying the strokes she used to beat past champions Maria Sharapova and Ana Ivanovic on the way to the final.
As soon as Safarova made things interesting enough Saturday to perhaps begin thinking about clutching the silver trophy, Williams quickly regained control, as she so often does.