— -- Flavia Pennetta capped one of the most unlikely runs in women's tennis history on Saturday with a 7-6 (4), 6-2 win over Roberta Vinci to win the 2015 US Open, her first -- and apparently last -- Grand Slam title.

Here's a look at five other Grand Slam champions that few saw coming.

<a href="http://abcnews.go.com/topics/sports/tennis/jennifer-capriati.htm" class="r_lapi">Jennifer Capriati</a>, No. 12 seed, 2001 Australian Open

She had been on the cover of Sports Illustrated at the age of 13, taken down Steffi Graf to win an Olympic gold medal at the age of 14, been the youngest player ever ranked in the Top 10, left the game, been arrested for marijuana possession, accused of shoplifting and entered rehab. And then, a 24-year-old Jennifer Capriati was finally a Grand Slam champion. Along the way Down Under, she took out nine-time Grand Slam champion Monica Seles and defending champion Lindsay Davenport before beating top-seeded Martina Hingis 6-4, 6-3 in the final. ''I can't believe this is happening,'' Capriati said during the trophy presentation. ''There is so much to say. I don't know where to begin. Who would have thought I'd ever make it here after so much has happened? If you believe, dreams do come true.'' Capriati would go on to win two more major titles before retiring after the 2004 season and was inducted into the International Tennis Hall of Fame in 2012.

Maria Sharapova, No. 13 seed, 2004 Wimbledon

Long before there was Sugarpova, there was a 17-year-old Russian who ended the Williams sisters' four-year reign at the All England Club -- in stunning and decisive fashion. Playing in just her seventh Grand Slam tournament and her first Grand Slam final, Maria Sharapova knocked off Ai Sugiyama in the quarterfinals and Lindsay Davenport in the semis before taking out two-time defending champion Serena Williams 6-1, 6-4 in the final. With the win, Sharapova became the first Russian to win Wimbledon, the lowest seed to win the title since Wimbledon began seeding players in 1927 and the third-youngest Wimbledon women's singles champion ever. "It's always been my dream to come here and to win," she said. "It was never in my mind I would do it this year." Sharapova, currently ranked third in the world, has gone on to win four more majors and the career Grand Slam.

Kim Clijsters, unseeded, 2009 US Open

Marion Bartoli, Venus Williams, Li Na, Serena Williams, Caroline Wozniacki. None of them could stop a 26-year-old unseeded Belgian -- and new mom. After taking two years off, Kim Clijsters, a former No. 1 and a former US Open champion, won her second Grand Slam title in just her third tournament since returning to the tour after giving birth. "It still seems so surreal," Clijsters said. "Because it wasn't in the plan. I wanted to come back here, get a feel for it, play a Grand Slam so I wouldn't have to come back next year and learn the new experiences all over." Instead, she defeated defending champion Serena Williams in a controversial semifinal -- think "foot fault" -- and topped Wozniacki in straight sets in the final. Clijsters would repeat as US Open champion in 2010. She retired after the 2012 season with 41 career titles, including four Grand Slams.

Francesca Schiavone, No. 17 seed, 2010 French Open

Italy's first Grand Slam women's singles champion pretty much came out of nowhere as well. A year before her breakthrough, at the 2009 French Open, Francesca Schiavone had been ranked 50th in the world and lost in the first round. At Roland Garros in 2010, the 29-year-old topped seeds Li Na, Caroline Wozniacki and Elena Dementieva en route to her first major final. Once there, in front of a box of family and friends wearing shirts that said "Nothing is Impossible," she beat Samantha Stosur 6-4, 7-6 (2) and became the oldest woman since 1969 to win her first Grand Slam championship. "This means that everybody has a chance," Schiavone said. "To be who you really want to be, and to do everything in your life. This is what's happened to me." Currently ranked 95th in the world, Schiavone has won two titles since and a total of six in her career. She is 568-430 in her career, including a first-round loss at the 2015 US Open to Yanina Wickmayer.

Marion Bartoli, No. 15 seed, 2013 Wimbledon

After other players knocked out the heavy hitters in the Wimbledon draw, 28-year-old Marion Bartoli emerged as the last one standing on the green grass. The Frenchwoman beat Sabine Lisicki, who had wiped defending champion Serena Williams out of the draw in the fourth round, 6-1, 6-4 in the final. It was Bartoli's 47th Grand Slam tournament, the most ever played by a woman before earning a championship (until Saturday). Not only that, it had been more than 1½ years since Bartoli had won a tournament at any level. "I can't believe I won Wimbledon this year," she said. "We'll have to see the pictures, to see the match again on DVD, to ... realize it." Six weeks later, Bartoli announced her retirement from tennis.

Flavia Pennetta, No. 26 seed, 2015 US Open

Sure, the 33-year-old Flavia Pennetta had been to the US Open semifinals in 2013 and been as far as the quarters in Flushing Meadows four additional times. But she had never played in a major final and carried a 17-15 record on the year into New York. And then she won seven straight. While it was her opponent in the final, unseeded Roberta Vinci, who knocked out three-time defending champion Serena Williams in the semifinals, Pennetta pulled off some stunners as well. She beat former US Open champion Samantha Stosur, two-time Wimbledon champion Petra Kvitova and second-seeded Simona Halep en route to the final, where she posted a 7-6 (4), 6-2 win. "I never think to be a champion," she said. "It's a big surprise also for me." Pennetta became the oldest woman in the Open era to become a Grand Slam champion for the first time. Then, during the trophy presentation, Pennetta announced her retirement from tennis. "I couldn't think to finish in a better way," she said.