The eighth-seeded American, who is now tied with Germany's Steffi Graf for the record of five Miami titles, triumphed on her eighth match point with an overhead smash.

"I thought I had 15 match points," joked Williams, who has a 47-5 record in Miami. "It was a couple of shots she hit really well a couple of times."

Williams, who also won the Bangalore title this year, closed out the opening set with an ace on her second set point in the seventh game in just under half-an-hour.

Leading 6-1 and 3-0 with two breaks in the second set, Williams was in control but then hit a sticky patch and surrendered three breaks to Jankovic in the fourth, 10th and 12th games.

"I was up and on my way to glory and out of there in an hour," Williams said. "When someone has nothing to lose and starts playing the match like you have nothing to lose those are the most dangerous people in life and on a court."

Serving for the match at 5-4, Williams made four errors and lost her serve leaving Jankovic to go on and win the set.

Both players turned down the offer of a 10-minute heat break between the second and third sets and Williams broke the Serbian world number three in the first game of the decider. Jankovic, who has suffered with a cold throughout the tournament, immediately called the trainer and complained that she had a headache and felt she was going to choke.

"It was really annoying for me to be sick and playing a final," said Jankovic. "I felt a little bit weak today. I couldn't breathe. I tried just to play the game and just enjoy it and have fun."

Williams took advantage and stormed into a 5-0 lead but just when it seemed she would serve out the match Jankovic came alive to clinch a service break when the American netted a forehand.

Williams, serving for the match for a third time at 5-2, let a 40-0 lead slip away and lost her serve again. She showed her frustration by smashing her racket against the court, which earned her a code violation for racket abuse. However, she was all smiles after a smash of a different kind clinched the title.

Bhupathi beaten

Mahesh Bhupathi and Mark Knowles’ quest for a third ATP doubles title this season ended in disappointment after a  2-6, 2-6 mauling at the hands of top seeds Mike and Bob Bryan in the finals.