The 29-year-old was defeated in straight sets by the former Wimbledon and US Open semi‑finalist Belinda Bencic in Melbourne.
Overnight, fellow Brit Sonay Kartal was also knocked out in the opening round of the Grand Slam.
Defending men’s champion Jannik Sinner has progressed after his opponent Hugo Gaston was forced to retire from the match.
Earlier, American Madison Keys started her women’s title defence with a nervy victory.
