Serena Williams, the 13-time grand slam champion, had hardly any clue that her loud Come on would cost her the U.S. Open title on Sunday. But that is what happened at Arthur Ashe Stadium, and she lost the women's final to ninth-seeded Samantha Stosur from Australia, 6-2, 6-3.

After losing the first set with a margin of four games, Williams, 29, seemed to grab some momentum in the first game of the second set. She hammered a powerful forehand. But when Stosur lunged at the shot, Williams shouted, Come on before the ball hit the ground.

Just after that Stosur's racket missed the ball and the scoreboard was then changed from 30-40 to deuce.

This was enough for chair umpire Eva Asderaki of Greece to assess Williams with a code violation and a point penalty that took the game away from her. As per the International Tennis Federation rules, Asderaki called Williams for hindrance, which interprets that her yell was a deliberate interference, Los Angeles Times reported.

During the first changeover of the set, Williams railed toward Asderaki and was heard to say, You're out of control. You're a hater, and you're just unattractive inside. Worse, she added: If you ever see me walking down the hall, walk the other way.

After the match, when Williams was asked about her reaction, she said, I don't even remember what I said, it was just so intense out there.

It's the final for me, and I was just - I have to go - I guess I'll see it on YouTube. I don't know. I was just in the zone.

Stosur, 27, better known as a doubles player, had been quite lucky to make it to the final. Three of her last four matches had gone three sets and she was involved in the longest women's match played at the U.S. Open and the longest tiebreak at a grand slam, Reuters reported.

I felt like I was definitely the underdog going into it, so maybe that kind of made me a little more relaxed going into this match, especially after my last grand slam final, Stosur said.

In 2005, Stosur won the Australian Open mixed doubles title and the U.S. Open women's title. In 2006, she won the French Open double title, but after that she had to take a break from the game due to Lyme disease.

Stosur was a finalist at the 2010 French Open. She is also a former world no. 1 on the WTA Tour in doubles with Lisa Raymond from the United States. Her career high in singles is world no. 4.