Lleyton Hewitt inspired Australia Gold to their first Hopman Cup win as they triumphed 3-0 against a United States side shorn of Serena Williams.
Williams suffered a recurrence of the knee injury that has hampered her heading into 2016 and was forced to retire from her singles match against Jarmila Wolfe, already 7-5 2-1 down to the world number 105.
"I thought I played a good match, regardless of what just happened. She is a tough opponent, knee or no knee," Wolfe said.
"I still had to fight for my own and had to serve well.
"It's a bit unfortunate as you don't get to play Serena very often and this tournament is made for it. I hope her knee gets better."
If good fortune gave Australia Gold the upper hand, Hewitt turned on the style to press home the advantage.
The veteran, who will retire following this year's Australian Open, defeated the powerful Jack Sock 7-5 6-4, clinically penetrating his opponent's fearsome serve to delight the home fans in Perth.
With victory in the bag, Hewitt and Wolfe secured a whitewash, defeating Sock and stand-in partner Victoria Duval 7-6 (7-4) 6-1.
In the Tuesday's other tie, Ukraine's Alexandr Dolgopolov and Elina Svitolina claimed singles victories over Czech pair Jiri Vesely and Karolina Pliskova to seal the tie, despite a second successive defeat in doubles.
The results leave United States out of contention to reach the final, with Ukraine best placed ahead of a final Group A meeting against Australia Gold.