Anna Kournikova has withdrawn from this week's grasscourt WTA tournament in Birmingham and the Eastbourne championships next week with a "chronic lumbar complaint", British tennis organisers said on Monday.
The 22-year-old Russian had been due to play Madagascar's Dally Randriantefy in the first round in Birmingham on Tuesday.
Randriantefy now plays lucky loser Adriana Serra Zanetti of Italy.
"I'm very disappointed, actually devastated not to be able to play in Birmingham," Kournikova said. "Grass is my favourite surface and I love playing in England, so having to pull out because of my back is the last thing I wanted.
"I arrived in England last Thursday and have been practising twice a day in Roehampton. I came to Birmingham on Sunday and practised. This morning I practised again.
"The trainer taped me for the practice, but after, I knew I had to see the trainer again.
"I've been advised not to play this week or next week and I don't know any further than that. They said my injury was chronic because it keeps coming back.
"It's the same problem I've had since after the Australian Open and it gives me referred pain in other areas, but it all comes from my back."
Kournikova has been plagued with injuries over the past two seasons and has not played on the WTA Tour since April's Family Circle Cup in Charleston, South Carolina, when she was forced to retire from her first-round match with a thigh strain.
Without a WTA title after spending more than seven years on the circuit, the Russian pin-up's off-court exploits have far overshadowed her tennis career.
Having reached the Wimbledon semi-finals in 1997 as a precocious 16-year-old talent, the Russian has since failed to deliver the goods on court.
Last month, she tried to rebuild her confidence on the lower ITF Women's Circuit tournaments following four first-round defeats in the five WTA tournaments she has played this year, but injuries once again hindered her progress.
Her world ranking, and confidence, have been on the slide since she reached a career-high eighth in May 2001.
Now ranked a lowly 77th, Kournikova is no longer considered a serious title contender on the WTA tour but remains the most photographed woman in sport.
