WHAT HAPPENED: The first-ever all-Italian Grand Slam final, pitting No. 26 seed Flavia Pennetta against Roberta Vinci, brought a crowd of famous faces, ranging from actress Queen Latifah to the prime minister of Italy. But it was Pennetta who brought her best tennis to the court.

Pennetta weathered a tight first set before storming through the latter stages of the match, defeating Vinci to win her first Grand Slam singles title, 7-6, 6-2.

Both players appeared nervous in the early stages of the match and struggled to find the range on their shots. Pennetta earned the first break at 2-2 in the first set, converting on her sixth opportunity after Vinci hit a slice backhand into the net. But three games later, a backhand sent wide by Pennetta on her serve leveled the match at 4-4.

In the first-set tiebreak, Vinci’s forehand began to betray her. A forehand into the net gave Pennetta a 5-3 lead, and another forehand sent long gave Pennetta a 6-4 advantage. The 33-year-old fired an unplayable first serve on her first set point to take the opening set.

Pennetta began to use her backhand up the line to great effect in the second set, hitting numerous winners off that wing. Meanwhile, Vinci began to hit her slice backhand off her back foot and started moving farther behind the baseline. Pennetta raced out to a 4-0 lead, and although Vinci was able to earn one of the breaks back, drawing within 4-2, the deficit was too much to overcome. Pennetta easily closed out the match on her first try, firing a forehand winner on her first championship point and raising her arms in disbelief at winning her first Grand Slam singles title.

Pennetta finished the match with 28 winners and 22 unforced errors, but her second set was significantly cleaner, with 11 winners and just three errors. Vinci also had more winners than errors in the second set but finished with 21 winners and 30 unforced errors on the day.

“It’s amazing to have the chance to play with one of your friends,” said Pennetta. “Before the match, we said it doesn't matter … it's going to be a really big win for both of us. I didn't think to be here. She didn't think to be here today, either. So it's amazing for our country. It’s amazing for everyone."

Pennetta, however, saved her most amazing moment for the on-court trophy ceremony, when she shocked the crowd by announcing that she is retiring from professional tennis after 15 years on tour.

“Before I started this tournament, one month ago, I made a big decision in my life. And this is why I would like to say goodbye to tennis,” she said to a stunned crowd. “I’m really happy. It’s what all players want to do, go home with one of these big trophies. So this one was my last match at the US Open and I couldn’t think to finish a better way. I want to thank everyone who supported me during my career. All my coaches, my family, who aren’t here, but they’re going to be proud of me. I love you guys.”

Despite the loss, Vinci was all smiles afterward, and said her run a this year's tournament was the greatest moment of her life.

"I think it's an incredible moment for all Italian people," she said. "Now when I come back home, I can realize what we made, because it's not normal for me now. ... But I would like to come back and try to understand what I did."

WHAT IT MEANS: At age 33, Pennetta is now the oldest first-time Grand Slam singles winner among women in the Open era. She also broke the record for most Grand Slam appearances (49) before winning a major. Her Cinderella run at this tournament has given the Italian her first title since March 2014 and only her second since 2010. She will now leap from No. 26 to No. 8 in the WTA rankings.

Pennetta also receives a $3.3 million check for winning the US Open this year, bringing her total career prize money to more than $13.5 million.

Despite her loss, Vinci will improve over 20 spots in the rankings from her current position of No. 43. She received a check for $1.6 million for reaching the final.

THE QUESTION: What do you think of Pennetta's decision to retire from the tour after winning her first Grand Slam singles title?