One point from losing the final in the Sony Ericsson Open, Williams hit a return that grazed the tape atop the net and skipped across to keep her chances alive. She won the ensuing rally, and more than an hour later she won her fourth Key Biscayne title.

Williams survived a dismal start and erased two championship points in the second set today to beat top-ranked Justine Henin 0-6, 7-5, 6-3.

''When I get down, a part of me just plays better,'' Williams said. ''I think all champions have that.''

The comeback was nothing new for Williams, who revived her career by winning the Australian Open in January for her eighth Grand Slam title. Once ranked No. 1, she fell to 140th last July because of long layoffs but will climb back to 11th next week.

Williams closed out the victory with a service winner, accepted gracious congratulations from Henin and waved her index finger for the cheering crowd, intent on returning to the top.

The match was 39 minutes old before Williams won a game, and she was twice one point from defeat with Henin serving at 5-4 in the second set.

''I said, 'I don't want to lose this fast. At least let it last an hour,''' Williams said.

Perhaps she learned how to deal with such stressful situations from her older sister. Serena was a spectator when Venus Williams fended off eight championship points to beat Jennifer Capriati in the 2001 Key Biscayne final.

With Henin serving at 40-15, Williams saved the first championship point by smacking an overhead winner after skipping her return off the net. She reached deuce by hitting a strong forehand to force an errant backhand by the Belgian.

Two points later, Henin slipped and took an awkward tumble, skinning her left knee, and she lost the next six points. She fell again trailing 3-0 in the final set and remained seated on the sunbaked concrete for nearly a minute, as if debating whether to concede.

The feisty Henin rose and rallied for 3-all, before Williams began one final surge.

''She's a fighter,'' Henin said. ''It's tough to close the matches against her, because she goes for it. She's a champion, and that makes a difference from the other players, for sure.''

Playing in only her seventh tournament in the past 18 months -- and her first since Melbourne -- Williams improved to 15-1 this year and 41-5 at Key Biscayne.

Two first-time Key Biscayne finalists will meet for the men's title tomorrow: 29-year-old qualifier Guillermo Canas and 19-year-old Novak Djokovic.

Williams vs. Henin was their first meeting in nearly four years. There were hard feelings in both camps after Henin beat Williams in the 2003 French Open semifinals, but they engaged in a warm conversation following the revival of the rivalry.

''The relationship is very good now,'' Henin said. ''We have a lot of respect for each other. We both agree that we are very good players. So what happened in the past is far away from now.''

Henin, a five-time Grand Slam champion playing in her first Key Biscayne final, used her vast array of shots to control the early rallies. Williams was off balance and struggled in vain to control the groundstrokes she used to overpower top-seeded Maria Sharapova and others in previous matches.

By the third game, Williams was flailing her arms in frustration. Two games later, she threw her racket. Then she screamed at herself. She lost the first six games for only the second time in her career, and won just six points in her first four service games.

''I figured I could do a little better,'' she said.

Williams finally won a game by breaking for 1-all in the second set, then needed 16 points in the next game to hold for the first time.

''I was making a lot of errors,'' Williams said. ''Justine was moving up to the ball and blasting winners. I had to lift the level of my game and stop making errors.''

The crowd -- including Miami Heat guard Dwyane Wade -- was in Williams' corner and roaring as she began to rally.