Tim Henman's Rome Masters campaign ended at the first hurdle as he lost in straight sets to Nicolas Almagro.
Henman was called into the event when David Nalbandian withdrew
Henman, who only made the draw when David Nalbandian withdrew on Saturday, lost 7-5 6-1 to the Spaniard on clay.
The British number two held his own until serving to stay in the first set at 6-5 down when Almagro pounced with a backhand on his second break point.
Almagro broke Henman's serve twice in the second set before closing out victory with an ace.
Henman's only ranking victory this year has been against Nicolas Mahut in Las Vegas in February but he insisted he had no thoughts of retirement.
"If I felt like my game was in poor shape then definitely it would be much more concerning," said the 32-year-old.
"I just have to try to be patient, but also I have to battle a little bit more. I could easily just say, 'This is not what I want to do' and throw in the towel. But I want to keep competing and work my way through it.
"If it doesn't happen on clay then I still feel coming onto grass if I'm in good shape then that will give me a lot more opportunities."
Almagro will now play world number one Roger Federer in the second round.
World number one Federer was in action on Monday, losing to big rival Rafael Nadal in the first round of the doubles event.
Nadal teamed up with his fellow Spaniard Carlos Moya to beat Federer and his Swiss Davis Cup team-mate Stanislas Wawrinka 6-4 7-6 (7-5).
Federer and Nadal, who is looking for his third straight Rome Masters title, are the top two seeds in the singles.
Former world number one Lleyton Hewitt was a high-profile casualty in the singles first round, losing 3-6 7-6 (7-3) 6-1 to Spaniard Oscar Hernandez.