In his opening ATP Tour match of the year, three-time grand slam winner Murray slipped up 6-3 5-7 6-3 against Bagnis, a player who began the year with a 30-59 win-loss career record.

Left-hander Bagnis rose to the occasion on Rod Laver Arena to earn the scalp of the former world No.1.

Murray, down at No.134 in the rankings after another injury-ravaged year, is looking to make headway on that front in 2022 under new coach Jan de Witt, so that he can avoid having to take wildcards into tournaments.

He was allowed into this tournament by that back-door route, and has also been confirmed for an Australian Open wildcard, but the Scot could not find the form that saw him beat Rafael Nadal at an exhibition event in Abu Dhabi in late December.

Bagnis said of his win: "In the beginning it was a pleasure to play against Andy and right now to beat him is amazing. I'm really happy."

He added: "Yesterday, I came to see the stadium, to see it all around because the atmosphere is different when you play on any court outside … I enjoyed it a lot. It was so good for me."

Nadal was also back in action on Tuesday, playing his first match on the main tour since August as he teamed up with fellow Spaniard Jaume Munar for a doubles win.

A foot injury meant Nadal's 2021 season ended early, but he warmed up for singles tests that lie ahead by joining Munar for a 6-3 3-6 10-4 win over Argentinians Sebastian Baez and Tomas Martin Etcheverry.