On a day she called "the perfect end" to her career, Roberta Vinci said goodbye to professional tennis on her terms in Rome. 

"It's not easy, but I was concentrated on this day," Vinci told reporters after a three-set defeat to Aleksandra Krunic in the first round of the Internazionali BNL d'Italia.

"A week ago, [I took] the calendar, and went, nine, eight, seven - a countdown. I know I practiced less than usual. When I saw that I play today, I was happy - I tried to enjoy my game, finish in a good way, and say 'Thank you,' to all the people. Here in Rome was the perfect end of my career."

The 35-year-old's storied WTA career lasted two decades, saw her reach the Top 10 in singles and the World No.1 ranking in doubles - where she and Sara Errani became just the fifth duo all-time to win all four Grand Slam titles. 

However, after a year-end ranking inside the Top 20 in four of the five seasons since 2012, Vinci fell outside the Top 100 to end 2017 - when she made the decision that the 2018 season, and, more specifically, the tournament at home in Rome, would be her last. 

"I decided at the end of last year, and I said, 'Okay, relax, and try to play three or four more months and say goodbye to all the people,'" Vinci said.

"I never changed my mind during these months, so I was completely sure that I wanted to stop. I tried to arrive here in good form, in good shape...but now, I'm good. I can relax."

Despite a decorated list of accomplishments, Vinci made herself a true household name on a fateful September day just under three years ago, when she produced the upset heard around the world. 

Unseeded, she came from a set down to stun Serena Williams in the semifinals of the US Open, ending the then-World No.1's bid for the calendar-year Grand Slam.

"A lot of time, a lot, a lot [I look back]! I had a lot of good memories. It's difficult to say something but...that was an incredible victory, the best victory of my life," Vinci reflected.

"The public can remember me with Serena, and the crowd and everything. It was an incredible day." 

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That victory propelled Vinci into the first-ever all-Italian singles final at a Grand Slam, where she fell to Flavia Pennetta in straight sets.

Nonetheless, it was that golden generation of Vinci, Pennetta - alongside Errani, former French Open champion Francesca Schiavone, and the also recently-retired Karin Knapp - which carried the flag for Italian tennis for the better part of two decades.

In addition to their individual accomplishments, the group were crowned Fed Cup champions on four occasions - in 2006, 2009, 2010 and 2013.

The Italian Fed Cup team with the 2013 trophies. (Getty)

"It was nice to stay in that group. We are good friends, we play a lot of times, Fed Cup, together," she said.

"Now, it changes. Flavia is already gone, now me..and Francesca, soon, maybe, I don't know, and the new generation is coming - but I was honored to play with them in this group."

For nearly 20 seasons, a throwback style of tennis saw Vinci excel around a one-handed slice backhand in an era of power baseliners.

"I had a difficult and different kind of tennis - I know it's an old style," she said. "You have to stay in good form, and you have to run a lot, and you have to think about every single shot."

However, it was that very game which took her to heights, and gave her the achievements which she said she is most proud of.

"All the results that I had. Top 10, slams, and I'm so proud of myself. [There were] ups and downs, of course, in this, but I'm really proud of my tennis, myself and my career," Vinci reflected.

"I tried my best, and I'm really proud of everything."