Serena Williams has captured her 15th Grand Slam title and fourth career US Open crown with a 6-2, 2-6, 7-5 victory over World No.1 Victoria Azarenka.
On Sunday, in the first three-set final at the US Open since 1995, US fourth seed Williams joined her sister Venus and Steffi Graf as the only women to win Wimbledon, the Olympics and the US Open in the same year.
The American showed all her great fighting qualities to claw her way back from the brink of defeat to become the oldest women's champion at Flushing Meadows in nearly four decades.
Against the odds after losing the first set, Azarenka looked to be on the verge of an unlikely victory when she led 5-3 in the decider.
She got within two points of winning the championship but was unable to prevent Williams reeling off the last four games in a row to seal her win and enhance her status as one of the greatest players the game has seen.
Earlier, Italy's Sara Errani and Roberta Vinci won their second grand slam title of the year when they beat the Czech pair Andrea Hlavackova and Lucie Hradecka 6-4, 6-2 at the US Open.
The number two seeds came through a tough opening set before running away with the second to add the US Open to the French Open title they won in June.
For Errani, it was the perfect pick-me-up after her defeat by Serena Williams in the semi-finals of the singles event.
"It is better to finish with a win," said Errani, who also reached the French Open singles final and who will go to the top of the doubles rankings on Monday, with Vinci rising to number two.
For Hlavackova and Hradecka, it was the third near-miss this summer, having lost to Serena and Venus Williams at Wimbledon and the Olympics.
"We should walk away from this tournament with a big smile," Hlavackova said.
Errani said becoming world number one was a dream come true.
"We played an amazing year so this is very important for us," she said. "We played good from Australia, where we made the final, and we won Paris. Of course it's an amazing year. We hope to continue."