Andy Murray suffered his first defeat of 2016 against Nick Kyrgios but Heather Watson kept Great Britain's hopes of victory over Australia Green at the Hopman Cup alive with a gutsy win over Daria Gavrilova.
Murray had won all four of his previous meetings against the flamboyant Australian but Kyrgios produced a largely mature performance to triumph 6-4 7-6 (7/5).
Gavrilova looked set to clinch victory for the home team in Perth when she led 5-3 in the decider but Watson won the final four games to triumph 6-7 (2/7) 6-2 7-5.
That ensured the match would be decided by the mixed doubles contest between the four.
Kyrgios broke serve in the third game of the match as Murray made an erratic start and that was enough for him to take the opening set.
The Australian broke again at the start of the second set but Murray hit straight back as his opponent's habit of going for the spectacular cost him.
Murray had a set point to level proceedings in the 12th game but Kyrgios held on and clinched victory on his second match point with a thumping forehand winner.
Murray complained of a sore hip after his first match against France's Kenny De Schepper and did not appear to be 100 per cent again.
Kyrgios backed his friend to be on top form at the Australian Open in under a fortnight, saying on hopmancup.com: "One hundred per cent he wanted to win that.
"I thought it was a good match. He's a true champion. He'll come back and I'm sure he'll be ready, and he's a strong contender for the Australian Open."
Gavrilova and Watson were engaged in a ding-dong battle that lasted two hours and 46 minutes.
Gavrilova saved two set points on her way to taking the opener but Watson turned things around and looked in control at 2-0 in the decider.
Gavrilova, ranked 19 places higher than Watson, fought back and served for the match at 5-3 but the British number two showed typical grit to come through.
Earlier, Germany, who Britain meet on Friday, won their first match of the competition 2-1 against France.
Caroline Garcia defeated Sabine Lisicki but teenager Alexander Zverev pulled Germany level with victory over De Schepper and the German duo won the doubles.
Meanwhile, Serena Williams withdrew from the tournament because of a knee injury and will not play in the USA's final match on Thursday.
The world number one missed the first match of the round-robin tournament and then retired during the second set of her clash against Australia's Jarmila Wolfe on Tuesday.
Williams revealed she was struggling with inflammation of her left knee and she will be replaced by Vicky Duval against the Czech Republic.
The injury must be a concern for Williams with less than two weeks to go until she begins the defence of her Australian Open title.
The 34-year-old brought an early end to her 2015 season partly because of pain in her knees after seeing her Grand Slam dreams ended by Roberta Vinci in the US Open semi-finals.