Penpix of the top women's contenders at the 2021 Australian Open:
Naomi Osaka (Japan)
World ranking: 3
Born: Oct. 16, 1997 (Age: 23)
Grand Slam titles: 3 (Australian Open 2019; U.S. Open 2018, 2020)
WTA career titles: 6
Best Australian Open performance: Winner (2019)
Osaka is coming off the most notable season of her career in which she won the U.S. Open, became the world's highest paid female athlete and used her profile to highlight racial injustice.
She heads to Melbourne in search of a fourth major crown that would leave her behind only the Williams sisters in terms of most Grand Slam titles among active female players.
The Japanese has a formidable blend of power and accuracy that helps her dictate rallies from the baseline but she felt a little rusty following exhibition matches in Adelaide.
Ash Barty (Australia)
World ranking: 1
Born: April 24, 1996 (Age: 24)
Grand Slam titles: 1 (French Open 2019)
WTA career titles: 8
Best Australian Open performance: Semi-finals (2020)
Having captured her maiden Grand Slam title in 2019, Barty was poised to kick on in 2020 but, after reaching the semi-finals at Melbourne Park for the first time, she opted to sit out most of the rest of the season due to the COVID-19 pandemic.
Unlike her rivals, Barty was not forced to quarantine ahead of the hard court major, potentially boosting her chances of becoming the first home-grown winner of an Australian Open singles title since Chris O'Neil in 1978.
Serena Williams (US)
World ranking: 11
Born: Sept 26, 1981 (Age: 39)
Grand Slam titles: 23 (Australian Open 2003, 2005, 2007, 2009, 2010, 2015, 2017; French Open 2002, 2013, 2015; Wimbledon 2002, 2003, 2009, 2010, 2012, 2015, 2016; U.S. Open 1999, 2002, 2008, 2012, 2013, 2014)
WTA career titles: 73
Best Australian Open performance: Winner (2003, 2005, 2007, 2009, 2010, 2015, 2017)
Williams last won a Grand Slam in 2017 and time is running out for the 39-year-old American to capture an elusive 24th title and equal Margaret Court's all-time record.
The delayed start to the Australian Open allowed Williams to shake off the Achilles injury that forced her to withdraw from her second-round match at last year's French Open and she has looked in fine form at this week's tune-up event in Melbourne.
Williams' scorching serves and punishing groundstrokes can subdue any opponent and she once again heads to Melbourne Park as the player to beat.
Simona Halep (Romania)
World ranking: 2
Born: Sept. 27, 1991 (Age: 29)
Grand Slam titles: 2 (French Open 2018; Wimbledon 2019)
Best Australian Open performance: Runner-up (2018)
WTA career titles: 22
Last year, Halep was not able to add to her two Grand Slam triumphs but she won titles in Dubai, Prague and Rome, racking up a 17-match winning streak.
The Romanian's speed, shot placement and remarkable anticipation have taken her to the top of the women's game but she lacks the physical strength of her biggest rivals and has a reputation for imploding under the spotlight.
Sofia Kenin (US)
World ranking: 4
Born: Nov. 14, 1998 (Age: 22)
Grand Slam titles: 1 (Australian Open 2020)
WTA career titles: 5
Best Australian Open performance: Winner (2020)
Kenin was named the 2020 WTA player of the year after a campaign in which she won her maiden Grand Slam singles title at the Australian Open and reached the French Open final, finishing the season ranked a career-high No. 4.
The 22-year-old defeated world number one Barty in the Australian Open semi-finals and twice Grand Slam champion Garbine Muguruza in the final during her run to the title last year and will look to pick up from where she left off.
Successfully defending her Melbourne Park crown will present a unique challenge, but Kenin's ability to thrive under pressure should hold her in good stead.
Iga Swiatek (Poland)
World ranking: 17
Born: May 31, 2001 (Age: 19)
Grand Slam titles: 1 (French Open 2020)
WTA career titles: 1
Best Australian Open performance: Fourth round (2020)
Iga Swiatek became the first Polish player to win a Grand Slam singles title when she beat Kenin in the French Open final last year. She climbed to a career-high 17th in the rankings and was voted the most improved player in the WTA awards.
Swiatek can generate easy power off both wings and possesses a temperament that belies her age, qualities that can help her thrive at Melbourne Park, although it remains to be seen how she deals with the spotlight of being a Grand Slam champion.