Emma Raducanu made a first-round exit at the National Bank Open in Toronto after losing in straight sets to defending champion Camila Giorgi.
World number 10 and ninth seed Raducanu was beaten 7-6 (0) 6-2 by the Italian world number 29, who was tournament winner in Montreal last year.
Raducanu lost in the Citi Open quarter-finals to Liudmila Samsonova in Washington last week and preparations for her US Open title defence later this month were dealt another blow in the city of her birth.
A winning start for the defending champ 👏
— wta (@WTA) August 9, 2022
The British teenager squandered chances to seize the initiative in either set and let slip a 2-0 lead in the second before bowing out in one hour and 49 minutes.
Both players lost serve three times in a hard-fought opening set before Raducanu dug deep to fend off set point in the 12th game to force a tie-break.
But the 19-year-old Briton lost her way and failed to win a single point as Giorgi forced four mini-breaks to seize control and take the first set after an hour and 11 minutes.
Raducanu, who had failed to convert game point for a 5-3 lead in the opening set, broke Giorgi’s first service game in the second to lead 2-0.
But Giorgi broke straight back and reeled off the next five games to set up a second-round clash with Belgium’s Elise Mertens.
Earlier, 10th seed Coco Gauff cruised into the second round by beating fellow American Madison Brengle 6-1 6-3, while Australian Ajla Tomljanovic, Spaniard Sara Sorribes Tormo and China’s Qinwen Zheng all progressed.