Germany's Nicolas Kiefer had his Australian Open preparations thrown into disarray after injuring his ankle during his Hopman Cup clash against Slovakia's Dominik Hrbaty in Perth on Thursday.
The 31-year-old German was leading 3-1 in the first set of the mixed teams round-robin event when he twisted his ankle and was taken off the court in a wheelchair, gifting the tie to Slovakia, who have advanced to Friday's final.
Slovakia's Dominika Cibulkova had earlier beaten Sabine Lisicki 7-6, 6-4 in the women's singles match.
Slovakia were awarded the mixed doubles tie on a walkover and progress to the final against Russia, France or Italy, who are all still in contention in Group B.
In the other Group A match on Thursday, James Blake and Meghann Shaughnessy combined to beat Australia 2-1 and consign the hosts to the bottom of the group.
World number 10 James Blake thrashed Lleyton Hewitt 6-2, 6-2 in an hour. It was a first loss in singles at the event for Hewitt, who is making a return after missing the tailend of 2008 because of a hip injury.
The former world number one appeared sluggish and complained of a problem with his ear.
"I'm not really sure what it is, I couldn't hear a lot out there," Hewitt told reporters.
"I sort of felt I was tripping over my feet out there for a while, so it wasn't the best situation to be in.
"The hip actually felt really good today, the best it's felt. So I was more frustrated with the ear and not being able to hear the ball properly.
"I couldn't pick up on it. My whole balance and routine was knocked out of whack."
Casey Dellacqua managed to record her first win of the event in front of her home crowd in Western Australia with a 6-3, 6-4 victory before Blake beat Hewitt then combined with Shaughnessy to win the mixed doubles in a tiebreak decider 6-3, 5-7, 7-6.