The sixth seed came from a game down on three occasion to complete a stunning 4-11, 11-9, 6-11, 11-7, 7-11, 14-12, 11-6 victory over Sun in the Croatian capital.

Sun had won their previous four meetings but it was Hirano’s day as the Japanese ace clinched her first-ever women’s singles crown on the WTT Series.

"I was well prepared to face Sun Yingsha in the final today, and I am very happy to win the match at the end," said Hirano.

"When I played Sun five years ago, I lost the match because I didn’t handle the last key score well.

"This time I handled key points more reasonably.

"When I was leading at 10-6 in the sixth set and was chased until 10-10, I should have been very anxious according to my normal mentality, but I think it is not easy to reach this point today, and I didn’t give up my belief in winning."

There was also a shock in the men’s singles final as Lin Gaoyuan upstaged world number one Fan Zhendong.

The all-Chinese contest usually goes the way of Fan but he struggled to assert his authority in the early stages against third seed Lin.

It turned out to be a thrilling encounter between two of the sport’s biggest hitters before Lin secured a 11-9, 6-11, 15-13, 12-14, 6-11, 11-9, 11-9 triumph.

"This was a difficult match," said Lin.

"Both of us played very well.

"I didn’t think too much before the match.

"I just wanted to let go and play.

"In this match, I have played a lot of wonderful shots and gained a lot.

"I have to say every game, every match here was a challenge for me."

Lin missed out on a second title on the last day as he teamed up with Liang Jingkun in an all-Chinese men’s doubles final only to lose to Lin Shidong and Yuan Licen 11-9, 13-11, 10-12, 11-4.

He also partnered Kuai Man in the mixed doubles final but lost to compatriots Sun and Wang Chuqin 11-6, 11-3, 9-11, 11-5.

Jeon Ji-hee and Shin Yu-bin of South Korea secured their second women’s doubles title in three weeks with a 11-6, 8-11, 8-11, 12-10, 11-8 triumph against Chinese pair Qian Tianyi and Liu Weishan.