Despite her inconsistency on the court in recent years, Serena Williams is now the most successful female athlete of all time, having overtaken golfer Annika Sorenstam as the highest earning sportswoman in history.

Williams had an unconventional path into the game, coached at home primarily by her father Richard, alongside her sister Venus, also a former world number one.

After upsetting former world No. 1s Mary Pierce and Monica Seles in 1997, Williams climbed from outside the top 300 to the top 100 in a year. However, it was not until 1999 that she really made an impact on the singles tour, winning her first title in Paris before beating 22-time Grand Slam winner Steffi Graf to win her second title and break into the top ten. She won her first Grand Slam title at the US Open to end the year ranked fourth. However, she failed to build on the success of the previous year. The highlight of 2000 was winning an Olympic gold medal in the women's doubles in Sydney, and finished the year ranked sixth.

In January 2001 Williams completed a career Grand Slam with her sister in the women's doubles after winning the Australian Open. The pair met for the sixth time later that year at Indian Wells, but Venus withdrew from the semi-final, prompting speculations that matches between the sisters were fixed. Williams beat Clijsters to win the title but she was booed throughout the final.

Williams became just the fifth woman in history to hold all four major titles at a time, winning all four Grand Slams between the French Open in June 2002 and the Australian Open in January 2003, in what was dubbed a 'Serena Slam'. Such was the dominance of the world No. 1 that she did not lose a single match in 2003 until April.

However, she was plagued by knee injuries and by 2006 she had fallen outside of the top ten. She won the 2007 Australian Open, but retired and withdrew from a number of events throughout the year with a host of problems, including knee, ankle and abdominal injuries and gum surgery.

But 2009 saw her back to her best, winning the Australian Open to knock Jelena Jankovic off the No.1 spot, and become the highest earner in the history of women's sports. Despite the fact that she held three of the four Grand Slam titles, she was only ranked second behind Dinara Safina, who had never won a major title.

She failed to win a title in the run-up to the US Open, for which she was favourite, but in bizarre circumstances lost in the semi-final to Kim Clijsters, who had recently returned from retirement. On her second serve trailing in the second set, Williams was called for a foot fault, which handed Clijsters two match points. Williams gestured to the line-judge who made the call and used threatening language, and Williams was penalised a point for unsporting behaviour, handing Clijsters the win. Although Williams was allowed to continue competing in the doubles' tournament, she was handed a fine and put on two-year probation.

In January 2010 Williams beat Justine Henin to win the Australian Open for the fifth time and drew level in the al-time list with Billie-Jean King after winning her 12th Grand Slam title, and she moved clear on 13 after a fourth Wimbledon title.

However, a foot injury followed by a major health scare saw her sidelined for nearly a year, returning to action shortly before the defence of her Wimbledon title. Lack of match practice saw her fail to reach the quarter-finals at the All England Club, but after titles in Stanford and Toronto, by the US Open she was the red-hot favourite. The No. 28 seed defeated four seeds en route to the final, but in straight sets to Australia's Sam Stosur, who won her maiden grand slam.

She did not have to wait much longer for her 14th grand slam, as she defeated Agnieszka Radwanska in three sets to claim a fifth Wimbledon title before making her career Grand Slam a golden one with victory at London 2012.

Later in 2012 she took her fourth US Open tittle, making that her 15th grand slam win. Victoria Azarenka pushed Serena to the limit, but was defeated in the third set as Serena added to her trophy cabinet.

Career high
Fresh from winning the French Open for the first time to move up to second in the world rankings, Williams beat her sister, the defending champion in the women's final at Wimbledon to win her third Grand Slam title and become No. 1 for the first time.

Career low
After a year dominating the women's game, including four consecutive Grand Slam titles, Williams was forced to miss the second half of the 2003 season with injury, and missed the chance to defend her US Open title after knee surgery. After seeing Kim Clijsters take the number one spot, while still recovering from surgery, her half-sister, Yetunde Price was murdered in a drive-by shooting in California.

Quotes
"Luck has nothing to do with it, because I have spent many, many hours, countless hours, on the court working for my one moment in time, not knowing when it would come."

"I'm a perfectionist. I'm pretty much insatiable. I feel there's so many things I can improve on."

"I got it wrong with Serena Williams. It still amazes me that the top women can play so little yet win. Either they are that good or the others are too inconsistent." Pat Cash

"I've come back in so many matches. Obviously, I would have liked to win easy. But this is a more exciting way to win. You don't know what to expect," Williams said following her US Open final win over Victoria Azarenka. "I honestly can't believe I won. I was preparing my runner-up speech because she was playing so great."

Trivia
Along with her sister Venus, Williams is a part owner of the NFL team Miami Dolphins.