ST PETERSBURG, Russia - Former World No.7 Belinda Bencic has won her first tournament on her return from left wrist surgery in the ITF $100,000 event in St Petersburg, beating 2016 Wimbledon girls' runner-up Dayana Yastremska, 6-2, 6-3 in the final.

Beset by a variety of injuries this year, the Swiss star had seen her ranking fall to No.312 after sitting out for five months.

"This victory means so much for me," Bencic said after the match. "I was thinking all time when I was home -- it was very tough, and I was doubting if I could play good again."

Her last on-court appearance was in Fed Cup doubles in April alongside Martina Hingis, winning the doubles dead rubber over Belarus's Olga Govortsova and Vera Lapko, and her last singles match was a first-round loss at the Ladies' Open Biel Bienne to Carina Witthoeft the previous week.

There were no signs of rust as the 20-year-old carved her way through a strong field this week.

Bencic began with an emphatic 6-0, 6-0 double bagel victory over 18-year-old local qualifier Anastasia Gasanova. She followed that by beating former World No.71 Vitalia Diatchenko 6-4, 6-3 and Ysaline Bonaventure 6-1, 6-2 to reach the semifinals.

"I think the toughest match of the tournament was in the second round against Diatchenko," Bencic assessed. "I think she has a very unique game and it was very difficult to play her. It was only my second match so I was very nervous again, but I managed to beat her."

In the final four, Bencic faced her toughest test against fellow 20-year-old and junior rival Anhelina Kalinina.

The Ukrainian, who reached a career high of No.148 in 2015, is also on the comeback trail, having sat out for 10 months in 2015-16 due to a shoulder injury.

The winner of three ITF $25,000 tournaments this year, Kalinina has hauled her ranking back to No.178, and she was the only player to take a set off Bencic this week.

Ultimately, though, the two-time WTA title-winner reprised her junior dominance over Kalinina to make the final 6-1, 4-6, 6-1.

Her opponent there was another Ukrainian, the hard-hitting teenager in Yastremska. On a nine-match winning streak following victory in the ITF $60,000 event in Dunakeszi, Hungary, Yastremska led No.1 seed Donna Vekic 6-3, 2-0 in the semifinals before the Croat retired with an injury.

"[The final] was a very difficult match," Bencic added. "I was very nervous -- obviously, I haven’t played a final for a long time, but I think I was very focused and I knew what I have to do tactically to beat her. I think she has a great future for sure. I can remember myself being 17, and I wish the best of luck to her."

"I think it was a good lesson for me that I had this injury, and I know how to deal with it now. When I played first point [of the week], I was smiling because I was back playing."

- Belinda Bencic

The 17-year-old Yastremska, who reached her maiden WTA quarterfinal in Istanbul in April, was unable to make a dent as Bencic swept to victory in the same city where she last reached a WTA final -- in February of last season.

"I love the city of St. Petersburg; I think it is so beautiful," Bencic said of electing to return to tennis at the event. "I saw good players here -- it was an opportunity, and I know the organization here and the people. I felt very welcome and I thought it is a good tournament to play as the first step.

"[Because of results here in 2016], I first reached the Top 10 -- so I think [the city] is good karma! I felt a lot of support as well...when I was playing. I always enjoy coming back here, and I hope to be back in February as well."