Former US Open champion Marin Cilic became the lowest-ranked player to win an ATP Tour title with an emotional victory at the Hangzhou Open.

Croatia's Cilic, who started the tournament at 777th in the world, has spent the majority of the past two seasons out with a knee injury which required multiple surgeries.

Given a wildcard to play in Hangzhou, the former world number three had not won an ATP Tour match in 22 months before this week.

On Tuesday, just four days before his 36th birthday, he beat home favourite Zhang Zhizhen 7-6 (7-5) 7-6 (7-5) to lift the title.

"It has been a difficult period for me - I lost my ranking and I didn't play too much," said Cilic, who reached a career-high ranking of third in 2018.

Cilic had the latest surgery on his right knee in May, saying it was the "best option" to help overcome the problem and return to court.

He played just two matches in 2023 and another four times at the start of this season.

The comeback began on the Challenger Tour - the tier below the main ATP events - in August before stepping up a level again over the past week in China.

Cilic hit 18 aces and won 42 of 50 first-service points (84%) against 43rd-ranked Zhang.

In his post-match speech, the 2014 US Open champion dedicated the victory to his family - including his wife and two children - for their support during the low moments.

"Everybody at home has been with me in this difficult period, working day by day, believing and pushing me, giving me strength and spirit," Cilic said.

"I'm happy to make this victory, not just for me, but for them. For everyone there is a small piece of this trophy."

On the back of winning a 21st title of his career, Cilic will rise 404 places in the rankings to 373 next week.