2003 Australian Open – Women's singles

Serena Williams defeated her sister Venus Williams in the final, 7–6^(7–4), 3–6, 6–4 to win the women's singles tennis title at the 2003 Australian Open. It was her first Australian Open singles title and fourth consecutive major singles triumph, completing the "Serena Slam", both a non-calendar year Grand Slam and the career Grand Slam. It was Venus' record fourth consecutive runner-up finish at a major, losing every final to Serena. The Williams sister became the first two players, female or male, to meet in 4 consecutive grand slam final in the Open Era (they would later be joined by Rafael Nadal and Novak Djokovic in 2011-2012). Serena saved two match points en route to the title, against Kim Clijsters in the semifinals (where at one point in the third set Serena was 1–5 down).

Jennifer Capriati was the two-time defending champion, but lost to Marlene Weingärtner in the first round. Capriati's loss marked the first time the defending Australian Open champion lost in the first round, and the first time at any major that the defending champion lost in the first round since Steffi Graf at the 1994 Wimbledon Championships. With Lindsay Davenport's defeat in the fourth round, a first-time Australian Open champion was guaranteed.

This marked the final Australian Open appearance of four-time champion Monica Seles; she lost to Klára Koukalová in the second round. This would also be the only time Seles lost before the quarterfinals at the Australian Open, and only the second time she lost before the semifinals, leaving with a 43-4 record, a 91.5% win rate.

It was also the first Australian Open final without Martina Hingis since 1996.

This marked the first major appearance of two future world No. 1's: five-time major champion Maria Sharapova and Jelena Janković, who lost to Klára Koukalová and Amanda Coetzer in the first and second rounds, respectively. It was also the major main draw debut of future US Open champion Flavia Pennetta, who lost to Silvia Farina Elia in the first round.

This marked the first of two times the sisters battled in an Australian Open final, with Serena also winning the 2017 edition of the year's first slam.