Amanda Anisimova overcame Naomi Osaka in the third round ©Getty Images

Defending champion Naomi Osaka suffered a third-round exit at the Australian Open after falling to a three-set defeat to the United States' Amanda Anisimova in Melbourne.

Anisimova headed into the match on a high after beating Olympic champion Belinda Bencic in the second round, but fell behind immediately with Osaka securing a break of serve.

The two-time Australian Open champion maintained her serve during the first set to claim the opener 6-4 on Margaret Court Arena.

Anisimova grew into the contest with the world number 60 breaking for a 3-1 lead in the second, with the 20-year-old then securing three confident holds to force the match into a decider.

The deciding set saw servers remain dominant, with a first-to-10 tiebreak required to settle the contest.

Anisimova edged clear of Osaka to win the tiebreak 10-5, with the American winning a thrilling match 4-6, 6-3, 7-6.

Anisimova's challenging route through the competition will continue, as world number one Ashleigh Barty will be her fourth-round opponent.

The home favourite continued her serene progress through the tournament with a third consecutive straight-sets victory, overcoming Italy's Camila Giorgi 6-2, 6-3.

French Open champion Barbora Krejčíková came from a set down to beat Latvia's Jeļena Ostapenko 2-6, 6-4, 6-4.

The Czech player, the tournament fourth seed, will face Belarus' Victoria Azarenka in the fourth round.

Azarenka overcame Elina Svitolina 6-0, 6-2.

Rafael Nadal overcame Karen Khachanov in four sets ©Getty Images
Rafael Nadal overcame Karen Khachanov in four sets ©Getty Images

American Madison Keys and Spain's Paula Badosa will compete for a quarter-final berth, after both players came through three-set matches.

Keys won 4-6, 6-3, 7-6 against China's Qiang Wang, while Badosa overcame Ukraine's Marta Kostyuk 6-2, 5-7, 6-4.

Fifth seed Maria Sakkari was a 6-4, 6-1 winner against Russia's Veronika Kudermetova, with the Greek player now set to face the US' Jessica Pegula, who beat Spain’s Nuria Parrizas Diaz 7-6, 6-2.

The men's singles draw saw the top seeds emerge unscathed, including 2009 winner Rafael Nadal.

The 20-time Grand Slam champion required four sets to beat Russia’s Karen Khachanov 6-3, 6-2, 3-6, 6-1.

Nadal, who missed the US Open due to a long-term foot injury, awaits the winner of the match between France’s Adrian Mannarino and Russia’s Aslan Karatsev.

Olympic champion Alexander Zverev continued his pursuit of a first Grand Slam title by beating Moldova's Radu Albot 6-3, 6-4, 6-4.

The German will face Denis Shapovalov in the fourth round, after the Canadian beat American Reilly Opelka 7-6, 4-6, 6-3, 6-4.

Italy’s Matteo Berrettini beat rising star Carlos Alcaraz of Spain in a five-set match, with the seventh seed edging the contest 6-2, 7-6, 4-6, 2-6, 7-6.

Berrettini will face more Spanish opposition in the fourth round, after Pablo Carreño Busta beat the US’ Sebastian Korda 6-4, 7-5, 6-7, 6-3.