Top seed Ashleigh Barty retained her Miami Open title after her Canadian opponent Bianca Andreescu was forced to retire with an ankle injury.
The Australian world number one was leading 6-3 4-0 in the first meeting between the pair.
The 2019 US Open champion had treatment from the trainer after she fell in the third game of the second set but was unable to complete the match.
"It's never the way you want to finish," said Barty.
"I feel for Bianca because she has had a lot of injuries and I hope it doesn't hamper her season too much.
"This is the first time I have defended a title and I'm excited we could kick-start a long season in the best possible way."
Barty had broken her opponent early in both sets and controlled the match after that, moving her opponent around the court.
She held serve in the opening game of the match and immediately broke before going 3-0 up.
Although the Canadian took advantage of an erratic service game from Barty to break back and close the deficit to 3-2, it was only a temporary reprieve as the Australian broke in the next game and continued to exert her dominance again to take the set.
Andreescu was soon under pressure in the second set, suffering an early break to go 2-0 down before the injury soon brought a disappointing end to her tournament.
Doubles disappointment for Evans and Skupski
Meanwhile, Dan Evans and Neal Skupski were beaten 6-4 6-4 in the men's doubles final by Croatian second seeds Nikola Mektic and Mate Pavic.
Evans and Skupski, playing together for the first time, became the third all-British duo to reach an ATP Masters 1000 final.
They fought hard against the second seeds, who had not dropped a set on their way to the final.
But their opponents, who have been the in-form pairing this year, proved too strong as they secured their fifth title of 2021.
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