2021 Australian Open – Men's singles

Two-time defending champion Novak Djokovic defeated Daniil Medvedev in the final, 7–5, 6–2, 6–2 to win the men's singles tennis title at the 2021 Australian Open. It was his record-extending ninth Australian Open title and his 18th major title overall. With his fourth round win against Milos Raonic, Djokovic joined Roger Federer as only the second man with 300 or more match wins in majors.

This marked the first major main-draw appearance for future world No. 1 and four-time major champion Carlos Alcaraz; he lost to Mikael Ymer in the second round. At 17 years old, Alcaraz became the youngest man to win a main-draw match at the Australian Open since Bernard Tomic in the 2009 Australian Open, defeating fellow qualifier Botic van de Zandschulp in the previous round.

Aslan Karatsev became the first male qualifier to reach a major semifinal since Vladimir Voltchkov in the 2000 Wimbledon Championships, and the first since Bob Giltinan in December 1977 to do so at the Australian Open. He was also the lowest-ranked player to reach a major semifinal since Goran Ivanišević (ranked 125) at the 2001 Wimbledon Championships, the lowest ranked to do so at the Australian Open since Patrick McEnroe (also ranked 114) in 1991, and the first man to reach a major semifinal in the Open Era on his main draw debut.

This was the first major in the Open Era to feature three Russian men in the quarterfinals, those being Karatsev, Medvedev and Andrey Rublev.

Seeds
All seedings per ATP rankings. • 🇷🇸 Novak Djokovic (champion)

• 🇪🇸 Rafael Nadal (quarterfinals)

• 🇦🇹 Dominic Thiem (fourth round)

• 🇷🇺 Daniil Medvedev (final)

• Stefanos Tsitsipas (semifinals)

• 🇩🇪 Alexander Zverev (quarterfinals)

• 🇷🇺 Andrey Rublev (quarterfinals)

• 🇦🇷 Diego Schwartzman (third round)

• 🇮🇹 Matteo Berrettini (fourth round, withdrew)

• 🇫🇷 Gaël Monfils (first round)

• 🇨🇦 Denis Shapovalov (third round)

• 🇪🇸 Roberto Bautista Agut (first round)

• 🇧🇪 David Goffin (first round)

• 🇨🇦 Milos Raonic (fourth round)

• 🇪🇸 Pablo Carreño Busta (third round, retired)

• 🇮🇹 Fabio Fognini (fourth round)

•  Stan Wawrinka (second round)

• 🇧🇬 Grigor Dimitrov (quarterfinals)

• 🇷🇺 Karen Khachanov (third round)

• 🇨🇦 Félix Auger-Aliassime (fourth round)

• 🇦🇺 Alex de Minaur (third round)

•  Borna Ćorić (second round)

• 🇷🇸 Dušan Lajović (fourth round)

• 🇳🇴 Casper Ruud (fourth round, retired)

• 🇫🇷 Benoît Paire (first round)

• 🇵🇱 Hubert Hurkacz (first round)

• 🇺🇸 Taylor Fritz (third round)

• 🇷🇸 Filip Krajinović (third round)

• 🇫🇷 Ugo Humbert (second round)

• 🇬🇧 Dan Evans  (first round)

• 🇮🇹 Lorenzo Sonego (second round)

• 🇫🇷 Adrian Mannarino (third round)

Ranking
The following are the seeded players. Seedings are based on ATP rankings as of 1 February 2021. Rankings and points before are as of 8 February 2021.

Wild cards
• 🇦🇺 Alex Bolt

• 🇦🇺 Thanasi Kokkinakis

• 🇮🇳 Sumit Nagal

• 🇦🇺 Christopher O'Connell

• 🇦🇺 Marc Polmans

• 🇦🇺 Alexei Popyrin

• 🇦🇺 Li Tu

• 🇦🇺 Aleksandar Vukic

Protected ranking
• Lu Yen-hsun (71)

• 🇺🇸 Mackenzie McDonald (83)

Qualifiers
• 🇪🇸 Carlos Alcaraz

• 🇧🇪 Kimmer Coppejans

• 🇺🇸 Maxime Cressy

• Frederico Ferreira Silva

• 🇫🇷 Quentin Halys

• 🇷🇺 Aslan Karatsev

•  Henri Laaksonen

• 🇨🇿 Tomáš Macháč

• 🇺🇸 Michael Mmoh

• 🇷🇺 Roman Safiullin

• 🇺🇦 Sergiy Stakhovsky

• 🇦🇺 Bernard Tomic

• 🇷🇸 Viktor Troicki

•  Botic van de Zandschulp

• 🇪🇸 Mario Vilella Martínez

• 🇸🇪 Elias Ymer

Lucky losers
• 🇯🇵 Taro Daniel

• 🇧🇴 Hugo Dellien

• 🇧🇦 Damir Džumhur

• Robin Haase

• 🇫🇷 Alexandre Müller

• 🇩🇪 Cedrik-Marcel Stebe

•  Mikael Torpegaard

Potential lucky losers

 * 1)  Borna Gojo (did not play)

Withdrawals
• 🇪🇸 Fernando Verdasco (65) → replaced by 🇦🇺 James Duckworth (103)

• 🇩🇪 Philipp Kohlschreiber (98) → replaced by 🇯🇵 Yasutaka Uchiyama (104)

• Roger Federer (5) → replaced by  Pedro Sousa (105)

• 🇫🇷 Jo-Wilfried Tsonga (62) → replaced by 🇮🇹 Andreas Seppi (106)

• 🇫🇷 Lucas Pouille (70) → replaced by 🇵🇱 Kamil Majchrzak (107)

• 🇬🇧 Kyle Edmund (48) → replaced by 🇧🇾 Ilya Ivashka (108)

• 🇺🇸 John Isner (25) → replaced by 🇧🇴 Hugo Dellien (LL)

•  Cristian Garín (22) → replaced by 🇯🇵 Taro Daniel (LL)

• 🇪🇸 Alejandro Davidovich Fokina (52) → replaced by 🇧🇦 Damir Džumhur (LL)

•  João Sousa (90) → replaced by 🇩🇪 Cedrik-Marcel Stebe (LL)

• 🇺🇸 Steve Johnson (72) → replaced by  Mikael Torpegaard (LL)

• 🇫🇷 Richard Gasquet (47) → replaced by  Robin Haase (LL)

• 🇦🇷 Federico Delbonis (82) → replaced by 🇫🇷 Alexandre Müller (LL)