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John Donegan, Associated Press
Serena Williams of the US makes a backhand return to Hungary's Greta Arn during their third round match at the Australian Open tennis championship, in Melbourne, Australia, Saturday, Jan. 21, 2012.

MELBOURNE, Australia — Serena Williams was so dominant in her 6-1, 6-1 third-round win over Greta Arn at the Australian Open that there's probably only one shot she'll remember more than most.

At 5-0 and a point from the first set, Williams lined up in the ideal position for overhead but then completely shanked it, spraying the ball wide. She screamed and put a hand over her face.

Arn saved another set point before holding serve for the first time. Williams responded by winning the next five games before Arn held again. The match ended in 59 minutes Saturday, on consecutive double-faults by Arn.

"I'm nowhere near where I want to be," said Williams, who has won her last 17 matches at Melbourne Park. "I'm just trying to play through it. A little rusty ... just trying to play through my rust."