Pennetta
Flavia Pennetta of Italy looks up at the U.S. Open Trophy after defeating compatriot Roberta Vinci in their women's singles final match at the U.S. Open Championships tennis tournament in New York, Sept. 12, 2015. Reuters/Carlo Allegri

Italian tennis pro Flavia Pennetta made a surprise announcement Saturday after winning her first Grand Slam title: She plans to retire from the sport.

“Before I started this tournament one month ago, I took a big decision in my life,” the 33-year-old told the crowd at Arthur Ashe Stadium in Flushing, New York. “This is the way I would like to say goodbye to tennis.”

Pennetta defeated her longtime Fed Cup teammate and friend Roberta Vinci in two straight sets, 7-6, 6-2. As she hoisted the trophy above her head, Italian prime minister Matteo Renzi watched -- and cheered -- from the stands.

Pennetta has won 11 career WTA singles titles, but never a grand slam.

“It’s a dream come true,” Pennetta told the crowd. “It was always my dream to win a grand slam.”

In many ways, the Pennetta-Vinci finals match was an unlikely one from the beginning. Vinci, an unseeded 30-year-old, won a surprise upset against top-ranked Serena Williams in Friday’s semi-final match. Pennetta was ranked at 26th.

On Twitter, Williams congratulated Pennetta for her win and post-match announcement.

“I want to thank everyone who helped me throughout my career, all my coaches, my family -- they couldn’t come, but I know they’re going to be really happy and proud of me,” Pennetta told the crowd. “Thank you for everything, you gave me a lot of emotion and I love you guys.”