Former world number one Rios retires

Marcelo Rios, the first South American player to reach number one in the world rankings, announced his retirement from tennis on Friday due to a back problem.

The 28-year-old had hoped to recover from the lingering injury but medical exams showed there was no hope of recovery.

"It's very sad for me to accept that I have to give up tennis. It has been the great passion of my life," Rios said during a news conference.

"The truth is, I wanted to keep on playing tennis, I think I could still achieve a lot more," he added.

Popularly know as "Chino Rios," he was also famous for his volatile temper.

He won 18 singles ATP titles in his career and in March 1998 became the world's best tennis player.

But he disappointed his tennis-mad Chilean fans -- and himself -- by never winning a Grand Slam. His best effort was a runner-up spot at the Australian Open in 1998.

After playing in the Davis Cup last July, Rios attempted to make a comeback by playing two events on the Challenger circuit earlier this year.

However, his failure to last the distance -- he retired in his last match in April -- have forced him to call time on his career. Rios said he had no firm plans for the future.

"I don't expect any tributes or acknowledgements," he said.