Japanese ninth seed Kei Nishikori crashed out of the French Open in the first round on Monday, clearly still suffering from his recent back injury.
Nishikori, 24, was the first Japanese man in 75 years to make the fourth round in Paris in 2013.
But on Monday, there was never any sign that he would repeat that feat as he went down 7-6 (7/4), 6-1, 6-2 to Slovakia's Martin Klizan in three minutes short of two hours.
Nishikori won the Barcelona claycourt title last month but then had to quit the Madrid Masters final against Rafael Nadal with a back injury that forced him out of the Rome Masters.
The world number 10 looked distinctly half-fit in Monday's cold, damp conditions on Court 1 where he was broken 10 times, hit 10 double faults and committed 40 unforced errors
Left-handed Klizan, one of six former junior champions in the main draw this year, was 2-0 ahead in the first set before Nishikori briefly rallied for a 5-3 lead.
However, Klizan reeled off 10 of the next 12 games on his way to a two sets to love lead.
The 24-year-old Klizan then broke in the first and fifth games of the third set as he moved smoothly towards victory.
Nishikori, coached by Michael Chang, the 1989 French Open champion, now faces a major battle to be fit for Wimbledon which starts in four weeks.
Klizan goes on to face Robin Haase of the Netherlands for a place in the last 32.