Britain's Katie Boulter was unable to build on a superb start as she lost to Italian top seed Jasmine Paolini in the last eight of the Merida Open.
Against the world number seven in Mexico, Boulter won the first set in 28 minutes without dropping a game.
But errors started to creep in as Paolini went on to win 0-6 6-3 6-3.
Having won only three points on her serve in the opening set, Paolini started the second set strongly, holding for the first time and then breaking to go 3-1 up.
Boulter, who came into the contest on the back of a seven-match winning run, including claiming the Ostrava Open title, broke straight back to love but neither player could hold serve in the next three games.