The 26-year-old broke Jankovic three times to take the opening set before saving four set points in the second to seal victory in two hours four minutes and regain the world number one ranking.

Williams, who swept away Russian Dinara Safina 6-3 6-2 in the semi-finals, fended off spectacular retrieving by Jankovic with her power game to clinch a third U.S. Open crown but her first here since 2002.

"I'm so excited," a beaming Williams said in a courtside interview. "It is that special because I've been working so hard.

"And I wasn't even going for number one and it's just like an added bonus."

On a warm night at Flushing Meadows, the fourth seed won a long opening service game but Jankovic, in her first grand slam final, held serve and broke to lead 2-1 when Williams netted a backhand.

The American then stepped up a gear, using her greater power to win four straight games to lead 5-2.

BROKE BACK

Jankovic held and broke back in the ninth game when her opponent netted a backhand but Williams broke for a third time to wrap up the opening set when the Serbian pushed a forehand long.

Williams held her opening serve in the second set but a scrambling Jankovic saved two break points in the next to stay on level terms.

The pair shared a series of exhausting rallies as they stayed on serve to 3-3, although Jankovic had to save another two break points to keep on terms.

Jankovic netted a forehand pass to hand Williams two break points in the sixth game but the Serbian saved both, before breaking to lead 4-3 when Williams netted a drop shot.

The Serbian held for 5-3 and when Williams trailed 0-40, she had three set points but the American saved them all before forging ahead 0-40 on the Jankovic serve.

In a marathon 10th game, Jankovic saved five break points and forced a fourth set point, only to double-fault and then lose her serve before Williams held to lead 6-5.