
Serena Williams lost to her sister Venus Williams on her return to the court at the Mubadala World Tennis Championship on Thursday (December 27).
Former world number one Serena was playing her first competitive match since she lost a controversial US Open final to Japan's Naomi Osaka in September.
Serena, 37, broke 38-year-old Venus' serve twice to win the first set, but faltered in the second, dropping three service games on the way to losing 6-3.
The contest went to a super tie-break.
While Venus dropped her opening serve, she outlasted Serena to win 10-8.
"Serena said I was playing well. I think we can only go up from here and that's our plan," Venus said after defeating the winner of 23 Grand Slam titles.
"It was really fun and so good to see everyone come out to support myself and Venus. It was really fun out here," Serena said.
The exhibition match is part of Serena's build-up for the Australian Open, where she will try to equal Margaret Court's tally of 24 grand slam singles titles.