British No 1 Kyle Edmund suffered a collapse at the Rolex Monte-Carlo Masters after losing 12 of the last 13 games to suffer a 4-6 6-3 6-1 first-round defeat to Diego Schwartzman.
In a match lasting just over two hours on Court Rainier III in Monaco, Schwartzman fought back in the second set as he won nine consecutive games to turn the match around.
Yorkshire’s Edmund, who was knocked out of last week’s Grand Prix Hassan II in Marrakech by Jo-Wilfried Tsonga at the second round stage, took the first set in 50 minutes against his Argentinian opponent, clinching it 6-4 in the 10th game against serve.
The 17th-seeded Brit raced to a 3-0 lead in the second set but Schwartzman hit back to level matters at 3-3 before going on to claim it 6-3.
The Argentine continued to dominate as he won the first three games of the third set – to extend his winning streak to nine games – before Edmund briefly stopped the rot to make it 3-1, but Schwartzman won the next three games to seal the win.
Next up for Schwartzman is a clash with the winner of the match between Tsonga and Taylor Fritz which is first on court on Tuesday.
The two will face one another again in the men’s doubles on Tuesday. Edmund and compatriot Neil Skupski are scheduled to play Schwartzman and Joao Sousa of Portugal.
British No 2 Cameron Norrie opens his singles campaign against Adrian Mannarino of France on the same day.
Rafael Nadal also begins his title defence against fellow Spaniard Roberto Bautista Agut. The match will be Nadal’s first in over a month after he injured his knee at Indian Wells in March.
American teenager Amanda Anisimova took her first career WTA singles title as she rallied from a set down to beat Astra Sharma in the final of the Claro Open Colsanitas in Bogata.