The main event of the BNP Paribas WTA Finals Singapore presented by SC Global has to be the singles competition, which starts on Monday at the Singapore Indoor Stadium.

Here is a quick guide of the eight tennis stars who will battle it out for season-ending honours in Singapore this week.

Serena Williams, 33 (USA)

World ranking: One. Win-loss (2014): 48-7.
Best results this year: Six titles, including the US Open. Past WTA Finals results: Ninth appearance. Won four times (2001, 2009, 2012, 2013)

Her participation was in doubt owing to an injury to her left knee, which forced her to abandon her title defence at the China Open. But on her day, the American is peerless. Since winning the 1999 US Open, Williams has carved out a great career, winning 18 Grand Slam singles titles, and over US$60million (S$77 million) in prize money.

At 33, the defending WTA Finals champion is hardly slowing down, winning six titles this season, including last month's US Open. Feared for her fast serves, powerful groundstrokes and aggression, Williams is undeniably the one to watch at the Singapore Indoor Stadium.

Maria Sharapova, 27 (Rus)

World ranking: Two. Win-loss (2014): 48-11
Best results this year: Four titles, including French Open. Past WTA Finals results: Seventh appearance, won in 2004.

Sharapova burst into prominence when she beat Williams to win the 2004 Wimbledon final. Since then, she has added four more Grand Slam titles, including this June's French Open.

The Russian beauty showed tremendous grit in battling back from a shoulder injury that limited her to just one match from June to December 2013, and is entering the tournament in good form, having won the China Open on Oct 5. With Williams hampered by a suspect knee injury, Sharapova is favoured clinch the WTA Finals title, and finish the year top of the world rankings..

Petra Kvitova, 24 (Cze)

World ranking: Four Win-loss (2014): 40-14
Best results this year: Three titles, including Wimbledon. Past WTA Finals results: Fourth appearance, won in 2011.

Kvitova surprised tennis observers when she won the 2011 Wimbledon as the eighth seed, beating Sharapova in straight sets. That same year, she also won the season-ending WTA Finals.

The Czech player repeated her Wimbledon triumph this year, routing Eugenie Bouchard in 55 minutes. Known for her rapid left-handed serves, Kvitova hit 36 aces en route to her 2011 Wimbledon triumph, the third-most by any woman in history. The world No. 4 also has three wins on the WTA tour this season.

Simona Halep, 23 (Rom)

World ranking: Three. Win-loss (2014): 43-14
Best results this year: Two titles. Past WTA Finals results: Making debut.

She may not have a Grand Slam title yet, but don't bet against the Romanian from upsetting the tennis establishment at the WTA Finals. The 23-year-old made several breakthroughs in her career this year, including achieving her highest world ranking (two) in August and reaching her first Grand Slam final in June's French Open.

Halep was named the WTA's Most Improved Player of 2013, en route to claiming six wins on the WTA tour last year.

Eugenie Bouchard, 20 (Can)

World ranking: Seven Win-loss (2014): 45-20
Best results this year: One title. Past WTA Finals results: Making debut.

In years to come, Bouchard will look back at 2014 as the year in which she arrived. She finished in the top four of the year's first three Grand Slams - the Australian Open, the French Open, and Wimbledon.

She also made her first Grand Slam final at Wimbledon, but fell to Kvitova. While she has just one career WTA title - the Nurnberg Open in May - to her name, her unique style, described as "aggressive" and "hard to read" by Ana Ivanovic, could see her claiming some scalps at the WTA Finals.

Agnieszka Radwanska, 25 (Pol)

World ranking: Six. Win-loss (2014): 46-19
Best results this year: One title. Past WTA Finals results: Sixth appearance.

A model of consistency, even though it has not been a spectacular year for the Pole, with only one title won in Montreal. Radwanska's career highlight has to be reaching the 2012 Wimbledon final, where she lost to Williams.

After a slew of bad results on the tour this year, such as crashing out in the round-of-64 at the US Open, she will be keen to make amends in Singapore.

Ana Ivanovic, 26 (Srb)

World ranking: Eight. Win-loss (2014): 56-16
Best results this year: Four titles. Past WTA Finals results: Third appearance.

The Serbian beauty has 15 WTA wins under her belt, including her only Grand Slam title - the 2008 French Open. Known for her aggressive style, the 26-year-old last topped the world rankings in 2008, and is entering the WTA Finals in good form, with four wins this season.

She also beat Williams in the Australian Open this year, and will be looking to topple her rivals on a playing surface that suits her playing style.

Caroline Wozniacki, 24 (Den)

World ranking: Nine. Win-loss (2014): 46-18
Best results this year: One title. Past WTA Finals results: Fourth appearance.

Wozniacki's 2014 would likely be remembered most for her high-profile break-up with golfer Rory McIlroy, although he WTA Finals represents a good chance for the Danish star to ensure it is her tennis that hogs the headlines.

She has been steadily making progress up the world rankings after falling to World No. 18 at one point, and has eight top four finishes, including winning the Istanbul Cup. on the tour this year.

Competition Format:
The eight players are divided into two groups, and play in a round-robin format. The top two qualify for the semi-finals, where the group winner will play the other group's runner-up, and then the final.

Doubles tournament
Besides the singles, eight doubles pairs will also vie for the Martina Navratilova trophy this week. Here are the pairs:

Sarah Errani/Roberta Vinci
The world No. 1 pair have five tour wins this year including winning the Australian Open and Wimbledon, and are the first to qualify for the WTA Finals. They are odds on to win the WTA Finals - the last major title missing from their trophy cabinet. If they emerge victorious, they will be only the third pair to win all four majors and the WTA Finals.

Hsieh Su-wei/Peng Shuai
The defending WTA Finals doubles champions won the French Open this year, the first of three wins on the tour this season. As a pair they have been successful with two Grand Slam wins, having also triumphed at last year's Wimbledon. This is their last tournament as partners, and both would want nothing better than to end their partnership with a win.

Cara Black/Sania Mirza
The pair teamed up in September last year, and showed immediate promise, beating top seeds Hsieh Su-wei and Peng Shuai en route to winning the Toray Pan Pacific Open that same month.

Ekaterina Makarova/Elena Vesnina
Last year's WTA Finals runners-up have two Grand Slam titles since teaming up in 2012 -- most recently, the 2014 US Open. Makarova's form is on the up, and achieved her highest singles ranking, No. 12, this month.

Raquel Kops-Jones/Abigail Spears
Top-ranked pair from the United States, and have two wins on the tour this year. Reached the Australian Open semi-finals, but the stacked WTA finals might be a step too far for them this year.

Kveta Peschke/Katarina Srebotnik
Their best moment came in 2011, when they won the Wimbledon. This is their fifth time playing at the WTA Finals.

Garbine Muguruza/Carla Suarez Navarro
The pair secured their berth in Singapore with one win on the tour, coming at the Bank of the West Classic in the United States.

Alla Kudryavtseva/Anastasia Rodionova
They booked their ticket to the WTA Finals thanks to three wins on the WTA tour this year, coming at the Brisbane Open, the Dubai Tennis Championships, and the Tianjin open.