Needed a shot of coffee to regain her best form during her opening match at the mixed teams Hopman Cup at the Perth Arena on Monday.
Perked up by a cup of coffee at the end of the first set, Williams recovered from a disastrous start to defeat Flavia Penetta as the United States beat Italy 3-0 in their Group A tie.
After Williams gave the Americans the lead, the towering John Isner then secured the tie with a grinding three-set win over Fabio Fognini.
Isner dropped the first set, but fought back to win 5-7, 7-5, 7-6 (7/4) in two hours and 27 minutes.
The Americans then survived two match points to claim the dead mixed doubles rubber in a match tiebreak, 6-2, 2-6, 11-9.
Williams, who will be aiming for her 19th Grand Slam singles title at the Australian Open later this month, had her hands full with 12th-ranked Pennetta in the early stages of her first singles match of the new year.
Pennetta raced through the first set in just 19 minutes, winning 6-0 as a listless Williams made a string of unforced errors.

Source: AFP