British number one Johanna Konta suffered her fourth straight singles defeat as she was knocked out of the St Petersburg Ladies Trophy.
Konta, 28, stepped up her return from a knee injury with a doubles win on Monday and, as the fourth seed, had a bye to the last 16 of the singles.
The world number 14 faced Oceane Dodin of France in just her third singles match since September’s US Open.
But Dodin, ranked 145 places below Konta, won 6-3 6-4 in Russia.
The first seven games went with serve before Dodin took control by winning five straight games.
Not only did that run earn Dodin the first set but the French number six, it also enabled her to take the decisive break in the first game of the second set.
Konta and Caroline Garcia, the French number two, will face Sweden’s Cornelia Lister and Renata Voracova of the Czech Republic in the doubles quarter-finals.
She opted to sit out Great Britain’s Fed Cup defeat by Slovakia at the weekend to protect her body.
But captain Anne Keothavong has said she will try to persuade Konta to make herself available for the play-off against Mexico on 17-18 April.