British number one Jack Draper suffered a second-round loss to Frenchman Arthur Rinderknech on his return to the ATP Tour at the Dubai Tennis Championships.
Contesting his first event on the men's tour since the US Open six months ago, Draper marked his comeback from injury by beating Quentin Halys in straight sets on Monday.
But the 24-year-old's tournament was ended by world number 31 Rinderknech in a 7-5 6-7 (4-7) 6-4 loss two days later.
Draper has slipped to 15th in the world, after reaching a career-high ranking of fourth last summer, following his long-term absence caused by a bruised bone in his service arm.