Canada's Leylah Fernandez won her third WTA title with a hard-fought victory over ailing Czech doubles specialist Katerina Siniakova at the Hong Kong Open on Sunday.

The 2021 US Open finalist triumphed 3-6, 6-4, 6-4 after two hours and 49 minutes at Victoria Park stadium.

Fernandez, ranked 60th in the world, has endured a lean couple of years after losing the Flushing Meadows final to fellow teenager Emma Raducanu two years ago.

"We had a very, very hard past couple of years," the 21-year-old said as she thanked her team.

"The hard work is paying off," said Fernandez, who won the Monterrey title in 2021 and 2022.

Fan favourite Fernandez, born in Montreal but with a Philippine background, also thanked the Hong Kong crowd for their support.

It had appeared the diminutive left-hander might be blasted off court as Siniakova broke her serve in the third game of the first set between the unseeded finalists.

The 85th-ranked Czech's groundstrokes were stronger and allowed her to move Fernandez around the court.

Siniakova's movement became restricted and she lost her first two service games of the second set before leaving the court for treatment.

She returned with her left thigh strapped and ground her way back to break Fernandez in the sixth game, the Canadian grimly hanging on.

Siniakova then crashed to the court after stretching for a Fernandez backhand in the first game of the deciding set.

She cried in pain and left the court for more treatment, returning with her right thigh bandaged as well.

Siniakova fought on, the players swapping four straight service breaks before Fernandez served out the match on her second championship point.

"Today was a very tough battle and I enjoyed every moment of it, so thank you for making this hard for me," Fernandez said to her opponent.