Serena Williams

Age: 38 • Country: United States • Rank: No. 8

Best Grand Slam result: 23-time champion

The Australian Open will commemorate the 50th anniversary of Margaret Court completing a Grand Slam in 1970 as Williams once again takes a shot at one of Court's tennis records. Last week in Auckland, New Zealand, Williams won her first tournament title since she returned to tour after giving birth to her daughter. A 24th Grand Slam singles championship, which would tie Court's record, still eludes Williams. She last won a major at the 2017 Australian Open.

Ashleigh Barty

Age: 23 • Country: Australia • Rank: No. 1

Best Grand Slam result: Won 2019 French Open

The top-ranked Barty is among the favorites — for bettors and fans. She arrives at her home major with a Grand Slam title under her belt from the French Open in June and having spent most of the past seven months at No. 1. An Australian woman has not won this tournament since 1978. Last year, Barty reached the quarterfinals, her best career result there in singles, but she faces a difficult draw.

Coco Gauff

Age: 15 • Country: United States • Rank: No. 66

Best Grand Slam result: Round 4, 2019 Wimbledon

Gauff became an instant sensation last July when, at 15, she upset Venus Williams in the first round of Wimbledon. From there, Gauff reached the fourth round of Wimbledon and the third round of the U.S. Open; she soared up the rankings from No. 313 to No. 66; and she won her first tour titles in singles and doubles. Gauff will face the 38-year-old Williams again to begin her first Australian Open.

Caroline Wozniacki

Age: 29 • Country: Denmark • Rank: No. 35

Best Grand Slam result: Won 2018 Australian Open

The Australian Open will be the last tournament for Wozniacki, the 2018 champion in Melbourne. Wozniacki, who learned in October 2018 that she has rheumatoid arthritis, announced last month that she will retire after this tournament. She reached three Grand Slam finals overall and was No. 1 from 2010 to 2012 and again in 2018.

Rafael Nadal

Age: 33 • Country: Spain • Rank: No. 1

Best Grand Slam result: 19-time champion

Nadal is one shy of Roger Federer's men's record of 20 Grand Slam singles titles. The fast hard courts in Melbourne have rarely suited Nadal well, and he has won this tournament only once, in 2009. Last year he was overwhelmed in the final by Novak Djokovic, a seven-time Australian Open champion and the favorite again this year.

Daniil Medvedev

Age: 23 • Country: Russia • Rank: No. 4

Best Grand Slam result: Runner-up, 2019 U.S. Open

Nadal, Djokovic and Federer, all in their 30s, have combined to win the last 12 major titles on the men's side. A man born in the 1990s has yet to claim a Grand Slam singles championship. Medvedev got the closest, pushing Nadal to five sets in a nearly-five-hour U.S. Open final in September. His quirky playing style has proved to be a good fit on hard courts, on which he won four titles last year.

Stefanos Tsitsipas

Age: 21 • Country: Greece • Rank: No. 6

Best Grand Slam result: SF, 2019 Australian Open

Tsitsipas finished last season strong by winning the year-end ATP Finals, and he beat each member of the so-called Big Three of Federer, Djokovic and Nadal at least once in 2019. This year he may have to beat all three, in a row, to win the title. Last year in Australia, Tsitsipas defeated Federer on his way to the semifinals, where he lost to Nadal. Melbourne has one of the largest Greek populations outside of Greece, and fans in its blue and white colors tend to come out in force at this tournament.

Andrey Rublev

Age: 22 • Country: Russia • Rank: No. 18

Best Grand Slam result: QF, 2017 U.S. Open

The hottest player on the men's tour had won 11 matches in a row entering Saturday's final at the warmup tournament in Adelaide. He is part of an emerging group of young Russians, including Medvedev and Karen Khachanov, who could be good for years to come.

Naila-Jean Meyers