Belgian fourth seed Joachim Gérard was beaten by Chile's Alexander Cataldo in the first-round of the Australian Open ©Getty Images

Belgium's Joachim Gérard was on the end of the biggest upset on the first day of wheelchair tennis competition at the Australian Open, losing his men's singles tie to Chilean Alexander Cataldo.

The fourth seed, who triumphed at the 2021 tournament, led after taking the first set 6-1 against Cataldo, but his opponent hit back to win the second and third sets 6-4 and 6-2.

Cataldo's reward is a quarter-final against Japan's Takuya Miki, who beat The Netherlands' Maikel Scheffers 6-1, 6-1.

The top half of the draw also featured wins for British pair Alfie Hewett and Gordon Reid.

Top seed Hewett, a runner-up in 2021 and 2022, eased past Japan's Daisuke Arai 6-1, 6-0, while former Paralympic champion and Tokyo 2020 bronze medallist Reid overcame The Netherlands' Tom Egberink 6-1, 3-6, 6-4.

Second seed Gustavo Fernández of Argentina beat The Netherlands' Ruben Spaargaren 6-3, 6-2 on Kia Arena, with Spain's Martín de la Puente defeating Australian wildcard Ben Weekes 7-5, 6-2.

Third seed Tokito Oda set up an all-Japanese quarter-final, beating the United States' Casey Ratzlaff 6-1, 7-5 while compatriot Takashi Sanada won 6-0, 3-6, 6-3 against British wildcard Ben Bartram.

The four seeded players all progressed in straight sets in the women's singles first-round.

The Netherlands' Paralympic champion Diede de Groot, seeking a fifth victory in six years at Melbourne Park, won both sets 6-1 against South Africa's Kgothatso Montjane on Kia Arena, with Momoko Ohtani of Japan her quarter-final opponent after she beat compatriot Saki Takamuro 6-2, 6-1.

Back-to-back women's singles champion Diede de Groot of The Netherlands beat South Africa's Kgothatso Montjane 6-1, 6-1 ©Getty Images
Back-to-back women's singles champion Diede de Groot of The Netherlands beat South Africa's Kgothatso Montjane 6-1, 6-1 ©Getty Images

De Groot's compatriot Aniek van Koot eased past Colombia's Angelica Bernal 6-1, 7-5, with Japan's Manami Tanaka beating Chile's Macarena Cabrillana 7-5, 6-1.

In the bottom half of the draw, Tokyo 2020 silver medallist Yui Kamiji of Japan whitewashed Britain's Lucy Shuker 6-0, with the US' Dana Mathewson her quarter-final opponent after a 6-3, 6-2 win against Argentina's María Florencia Moreno.

Fourth seed Jiske Griffioen of The Netherlands thrashed Germany's Katharina Krüger 6-1, 6-0 and Zhu Zhenzhen of China won the day's other match 6-3, 6-2 against Japan's Shiori Funamizu.

There were a few upsets in the quad singles as well, top seed Niels Vink of The Netherlands thrashing Brazil's Ymanitu Silva 6-1, 6-0 and his compatriot Sam Schröder, the defending champion and Paralympic silver medallist, beating home favourite Heath Davidson 6-1, 6-2.

Vink is set to play Donald Ramphadi of South Africa in the semi-finals after a 7-6, 3-6, 6-1 win against Canada's Robert Shaw, with Schröder taking on the US' David Wagner after a 6-3, 6-3 victory against Andy Lapthorne of Britain.

The men's and women's wheelchair singles quarter-finals and quad semi-finals are set to be played tomorrow.