Just because she's No. 1 in the world doesn't mean Serena Williams isn't infallible.

Tennis.SI.com reported that during Williams' 6-4, 6-4 victory over Andrea Petrovic at the Brisbane International, she whiffed on a swing volley that likely would've been a winner had she connected.

The miss caused a reaction from the Brisbane crowd and a smile from Petrovic as Williams herself couldn't decide whether she wanted to be disgusted or laugh it off as well.

Williams still finished the match with 35 winners and 11 aces, including one that traveled 122 mph. She did have 36 unforced errors.

"It was an intense match, which was really good for me," Williams told reporters. "She's a good player. She's been in the top 10 before and she was on her way to being even better."

According to Australia's The Courier-Mail, Williams took a Brisbane River cruise boat on her day off following the first-round win.

She told the newspaper that she hadn't yet had a chance to check out Brisbane or get in a little shopping. So naturally, she decided to go between matches.

"I haven't really done any shopping or anything else," she said.

The other shocking development besides her whiffed shot was a more blonde hair color.

""I went really blonde in Thailand... I decided I wanted to go a lot lighter with my hair," she said of the new 'do.

"So I just randomly had this guy do it."

Williams was expected to do some cruising during her second-round match against Slovakia's Dominika Cibulkova.