Cameron Norrie was outclassed by American rising star Sebastian Korda as Britain's bid in the Australian Open singles made an inauspicious start.
On day one in Melbourne, the British men's number one - who was seeded 12th - lost 6-3 6-0 6-4.
Norrie, 26, looked a shadow of the player who enjoyed a stellar 2021, losing nine games in a row from the end of the first set to 43rd-ranked Korda.
Five more Britons, led by Emma Raducanu and Andy Murray, play on Tuesday.
Dan Evans, Heather Watson and Liam Broady, who qualified for the men's draw for the first time in his career, are also in action.