Spain's Fernando Verdasco claimed a second title five years after his first at the Kooyong Classic on Friday when opponent Alexandr Dolgopolov was forced to retire with a knee injury.
With the Australian Open starting on Monday, the Ukrainian now fears he will not be able to play after feeling pain in the first set and retiring after losing the opener against his 31-year-old opponent 7-6 (7/3) in 44 minutes.
"I may need surgery," said world number-23 Dolgopolov, who missed more than two months in August and September with injury problems.
"I'm not sure even if I can play the Australian Open."
Verdasco won the title at the eight-man Grand Slam tune-up in 2010, beating France's Jo-Wilfried Tsonga.
"This is the last way you want to win a match," said Verdasco. "I'm good friends with Alex and you don't want this to happen to anyone.
"He was feeling pain in the set and that is not good news. It's not a matter of me getting in enough practice, I could practise all afternoon now if I want."
Verdasco admitted he had been husbanding his physical resources after playing at Kooyong on Wednesday and then going on court at Melbourne Park at night in an exhibition with Rafael Nadal.
"You don't want to use up all of your energy in the days before a grand slam. We had tough conditions and it was tough to hit three good shots in a row here because of the wind."
The Spaniard will use the win to bolster confidence when he plays Spanish-speaking Briton James Ward in the Open first round.
With one day a total washout of the four-day special event, compromises had to be made with scheduling.
As a result, the 33rd-ranked Verdasco and Dolgopolov reached the final as a result of winning their only other matches this week in straight sets.
In the playoff for third place, Frenchman Richard Gasquet beat Japan's Kei Nishikori 7-6(7/4), 7-6 (8/6).
Gasquet, who seemed to struggle with his back for a time in the second set, said later that he did not have a problem.
"I feel good, I don't have any big problems," said the Frenchman, who suffered through injuries in 2014 which dropped his ranking to its current 26th.
"I'm feeling good now and working on my fitness."
Gasquet will begin at next week's start of the Australian Open against Argentine Carlos Berlocq.
Nishikori also got in some prime practice for the major at Melbourne Park.
"The first set was tough with windy and hot conditions, and Richard played very well," said the US Open finalist. "In the second set I raised my level and played well. It was a matter of a few points."
Gasquet spent an hour and three-quarters in beating Nishikori for a sixth time after five wins at the ATP level over the world number five.