MIAMI: World number one Ashleigh Barty retained her Miami Open title Saturday as Bianca Andreescu's injury curse struck again.

Australia's Barty completed a 6-3, 4-0 victory after Andreescu was forced to retire in tears with an injury to her right ankle in the second set at the Hard Rock Stadium.

Barty had dominated the Canadian world number nine throughout the contest behind a powerful service game and accurate forehand.

The end came soon after the third game of the second set, when Andreescu collapsed to the court after rolling her right ankle during her service game.

Barty broke for a 3-0 lead as Andreescu, clearly struggling to move properly battled on. Despite being heavily strapped on her ankle, Andreescu retired soon afterwards, unable to continue.

It was a bitterly disappointing end for Andreescu, the 2019 US Open champion who missed the first few months of the 2020 season with a knee injury before last year's pandemic shutdown.

"Definitely not the way I wanted to end the tournament, but I'm super-grateful nonetheless," Andreescu, 20, said in comments on court after her defeat.

"I got to the final in one of my first tournaments in a while and I couldn't be more happy."

Andreescu revealed that she had initially wanted to play through the pain until being told to retire by her trainer.

"I really didn't want to stop but my fitness trainer, he basically saved me from myself," Andreescu said.

"I have been through that, just continuously pushing myself to the point where I'd make it worse. I trusted him. I knew it was the best decision."

Barty, meanwhile, was left to reflect on a clinical victory in what was her first overseas appearance since the WTA Tour resumed after the shutdown.