Novak Djokovic

The Serb is back at Melbourne Park for the first time since winning his ninth title in 2021 and says he "likes his chances". He was kicked out of the country ahead of the tournament last year over his Covid vaccination stance.

The 21-time Grand Slam winner also missed the US Open for the same reason, but won Wimbledon and is heavy favourite at his most successful major despite a niggling hamstring injury.

Now 35, the former world number one finished a troubled 2022 with a record-equalling sixth ATP Tour Finals crown and began the new year in irrepressible form, winning his 92nd career title at the Adelaide International.

"I know when I'm healthy and playing my best, on this court (Rod Laver Arena) I have chances really against anybody," he said.

Rafael Nadal

The 36-year-old Spaniard made the most of Djokovic's absence to win the title in 2022, outlasting Daniil Medvedev over five sets in a more than five-hour thriller.

He made history in the process -- the first man to achieve 21 Grand Slam singles crowns, making it 22 when he won a 14th French Open title.

But injuries hampered his season and he withdrew from Wimbledon after winning his quarter-final and exited in the last 16 at the US Open.

Now a father, Nadal struggled to find his best form at the ATP Finals in November and lost both of his matches at the recent United Cup, to Cameron Norrie and Alex de Minaur.

He is top seed in the absence of Alcaraz and insisted "my personal momentum is not bad, I tell you. I am good and happy."

Daniil Medvedev

The 26-year-old Russian was unable to match his run to the Melbourne final at the French or US Opens last year and never had a chance at Wimbledon after being banned due to the Ukraine war.

He did win two titles and spent 16 weeks as world number one.

But it was an underwhelming year in the eyes of the 2021 US Open champion, who has slipped to eight in the rankings.

He began 2023 at the Adelaide International, where he was beaten by Djokovic in the semi-finals.

"Every time I play them (Djokovic and Rafael Nadal), before the match the only thought is I have to win," he said.

Stefanos Tsitsipas

The world number four burst onto the scene at the Australian Open in 2019 when as a 20-year-old he dethroned defending champion Federer in the last 16.

He went on to reach the semi-finals that year and again in 2021 and 2022, highlighting the consistency that has made him a mainstay of the world's top 10 for nearly four years.

The Greek star won the ATP Masters 1000 title in Monte Carlo last year along with another on the grass of Mallorca.

But a Grand Slam crown remains elusive with his runner-up showing at Roland Garros in 2021 his best result at a major.

He began the new season on the Greek team at the United Cup, winning all four matches including the scalps of Matteo Berrettini and Grigor Dimitrov.

Nick Kyrgios

Love him or hate him, Kyrgios is a showman and nowhere more so than on home turf in Melbourne, drawing huge and rowdy crowds.

While his frequent tantrums have long overshadowed his talent, the enigmatic Australian had a stellar 2022, making a barnstorming run to a first Grand Slam singles final at Wimbledon, losing to Djokovic.

He has never gone past the Australian Open quarter-finals and his build-up has been hampered by an ankle injury, but the unpredictable Kyrgios is an outside chance if he can handle the pressure and keep his cool.