Johanna Konta was knocked out of the Porsche Grand Prix in the second round by Latvia's Anastasija Sevastova.
The British No 1 is inexperienced on clay at the highest level and it showed in a scrappy 6-3 7-5 loss to Sevastova, who also won their meeting at the US Open last year.
Wednesday's first-round victory over Naomi Osaka in Stuttgart was just Konta's third WTA Tour win on clay.
She began well with a break of Sevastova's serve in the first game but lost the next three games and did not hold her own serve until the fourth attempt.
Sevastova, ranked 19 places below Konta at 26, produced three aces in a row on her way to clinching the opening set and then recovered from 3-1 down in the second to level.
A missed forehand opportunity then cost Konta as she was broken in the 11th game and Sevastova served out the victory with her sixth ace.
The result meant there would be no immediate rematch between Konta and Romania's Simona Halep.
The pair met last Sunday in the fiery Fed Cup clash between Romania and Great Britain in Constanta, with Halep winning 6-1 6-3.
The world No 5 said she had been given extra motivation by the previous day's events, when Konta had left the court in tears during her clash with Sorana Cirstea after saying she felt threatened by abuse from the crowd in Halep's home city.