MELBOURNE, Australia (Reuters) - German tennis star Steffi Graf returns the ball at during the 1999 Australian Open. Graf, speaking in Heidelberg Friday, announced that she was retiring after a career spanning more than 15 years with 22 grand slam titles. The former world number one, 30, told a news conference she was quitting immediately. Photo by Tom Szlukovenyi

HEIDELBERG, Germany (Reuters) - A series of injuries forced German Steffi Graf to announce her retirement Friday after a career which brought her 22 grand slam titles in a career stretching back to 1982.

The former world number one, 30, told a news conference in her home town of Heidelberg she was quitting the game immediately.

``I have decided to stop playing tennis tournaments,'' she said. ``I have no regrets because I have the feeling I have achieved everything I could.

``There were quite a few misunderstandings over what I said over the last few weeks. I wanted to end all that speculation.''

The seven times Wimbledon champion, who has been persistently hampered by injuries over the past few years, said last month she would stop playing major tournaments at the end of the year.

She was hoping to play her 54th and last grand slam tournament at the U.S. Open in September but a strained left hamstring, which forced her out of a tournament in California earlier this month, made her change her plans.

``The weeks after Wimbledon were not easy at all,'' she said. ``For the first time I missed the joy of playing tennis. It was a strange feeling, which I had never experienced before.''

``So I thought I would carry on playing until the end of the year.''

``But I do not feel like flying to tournaments anymore. That's new. I decided to play a few more tournaments to see if that feeling would go away but it didn't.

``In the end it was an easy decision to take, much easier than I expected.''

The pony-tailed blonde with the devastating forehand became the youngest player to receive a WTA ranking at 13 years and four months in 1982.

She won 107 tournaments and held top spot for 377 weeks, an all time record. In 1988 she won the grand slam of the four major tournaments plus the Seoul Olympic title.