Cameron Norrie fell to an early exit at the Monte Carlo Masters as he lost to Francisco Cerundolo in the first round.
The British number one, ranked 13th in the world, was beaten 6-3 6-4 by Argentina’s Cerundolo on the Mediterranean clay.
Fellow Briton Jack Draper returned from injury with a 6-3 7-5 win in his opening tie against another Argentine, Sebastian Baez.
The 21-year-old faces 10th seed Hubert Hurkacz of Poland in the second round.
Draper was forced to retire during a fourth-round match with world number two Carlos Alcaraz in Indian Wells last month because of an abdominal problem. He then pulled out of the Miami Open as he did not want to make the problem worse.
He was given a strong test against Baez in Monte Carlo but saved 11 of the 12 break points he faced while taking three of his own four chances.
In his match, Norrie looked unsettled throughout and had 18 unforced errors compared with only eight winners.
World number 33 Cerundolo, 24, gained the decisive break in the ninth game of the second set when 27-year-old Norrie netted a forehand.
Norrie started the season with a run of 21 wins from 25 matches but also lost his opening match at the Miami Open last month when he was defeated by France’s Gregoire Barrere.
Later on Monday, three-time Grand Slam winner Andy Murray plays Australia’s Alex de Minaur.
