British number one Dan Evans was unable to earn a clay-court win before next week's French Open after losing to Greek second seed Stefanos Tsitsipas in the Hamburg Open first round.
Evans, ranked 34th, lost 6-3 6-1 as world number six Tsitsipas showed his quality in a 59-minute win.
Evans will head to Paris for the Grand Slam event which starts on Sunday.
Liam Broady could join him in the main draw, but must beat Botic van de Zandschulp later on Wednesday.
British number six Broady plays the Dutchman in their second qualifying match at Roland Garros and victory would leave the 26-year-old one more win from playing in the main draw for the first time.
Fellow Briton Samantha Murray Sharan was also aiming to reach the main draw of the women's singles for the first time, but lost 6-3 7-6 (7-1) to Australia's Arina Rodionova in her opening qualifier.
Meanwhile, British men's number three Cameron Norrie suffered a shock defeat at a Challenger event in Italy.
Second seed Norrie, who is ranked 71st in the world, lost 6-2 6-4 to Italian world number 343 Andrea Pellegrino.