Serena Williams crashes out of U.S. Open in one of the most stunning upsets in tennis history

Serena Williams' hopes for a calendar grand slam were dashed as she was eliminated from the U.S. Open by 43rd-ranked Italian player Roberta Vinci.

Serena, the world No. 1 and the heavy favorite to win the U.S. Open, looked like she would cruise to an easy win after winning the first set 6-2.

However, in the second set, Vinci stormed back to win 6-4, setting up a dramatic third set. Though Serena was up 2-0, Vinci once again stormed back, breaking Serena to go up 4-3 and then winning the next game.

Serena moved the score closer to make 5-4, but lost the following set as Vinci served.

Serena seemed fatigued by the third set, perhaps because she's hardly ever pushed to such lengths. According to ESPN, Williams' unforced errors kept growing by the set:

 

The final