Serena Williams orders coffee midway through match in Perth

World number one tennis star Serena Williams ordered coffee midway through her match against Flavia Pennetta at the Hopman Cup in Perth on Monday.

After losing the first set 6-0, the American sportswoman, who has 18 Grand Slam titles to her name, had a shot of espresso and went on to seal the victory 0-6 6-3 6-0.

"I am a coffee drinker and I didn't have mine this morning and I was just feeling it," The Sydney Morning Herald quotes Williams as saying. "So I had to get some coffee in me.

"I told them to just give me a shot of espresso. I asked them if it was legal - 'is it illegal to have a shot of espresso?' because I never did it before. I needed some espresso. I needed to wake up - the jetlag gets you all the time."

Williams ended the 2014 season by winning a fifth WTA Finals title.