Krunic, who had rallied from 5-2 down in the second set before winning it in a tiebreaker, earned a spot in the quarterfinals with the 5-7, 7-6 (3), 1-2 result after almost two and a half hours in humid conditions in Pat Rafter Arena.
“I don’t really cramp a lot, so I’m actually surprised that today my body was like that,” Muguruza said. “It’s a shame because I always come here excited about the first tournament, and this one was bad luck, I guess.”
The Brisbane International was Muguruza’s only scheduled tuneup event before the Australian Open, the first major of the season, begins in Melbourne on Jan. 15.
The 30-year-old Murray is also undecided. He said he was planning to stay in Brisbane for a few days before deciding whether to play in the Australian Open or fly home.
Murray said he had been trying to rest and rehabilitate the problematic right hip but realized after some practice sets in Australia against leading players that he was not quite fit for competition.
“Obviously continuing rehab is one option and giving my hip more time to recover,” Murray wrote in an Instagram post. “Surgery is also an option but the chances of a successful outcome are not as high as I would like which has made this my secondary option and my hope has been to avoid that.”
Murray, a five-time Australian Open runner-up, has not played a competitive match since his quarterfinal exit at Wimbledon, and his ranking has slipped from No. 1 to No. 16.
He is not the only leading player trying to overcome injury: Top-ranked Rafael Nadal and Novak Djokovic, currently No. 12 in the world, also trying to recover in time for the Australian Open.