Tennis legend Martina Navratilova, who beat breast cancer after seven months of treatment, said it was the first opponent she feared might beat her.

At the start of the year, the nine-times Wimbledon champion said she was devastated on being diagnosed with breast cancer. But now, after seven months' treatment, she said she has "beaten it", The Mirror reported.

"The worst part was the first day. I was alone. I had no one to lean on. But the response was great and I know I've saved some lives," Navratilova was quoted as saying.

She said that when she learnt she had the malignant tumour in her left breast, it was by far the worst experience of her life.

"It knocked me on my ass, really. I feel so in control of my life and my body, and then this comes. Throughout my tennis career I have faced some really tough opponents across the net. What I never anticipated was that my toughest opponent would be off the court, cancer," she added.

Photographs: Reuters

But Navratilova, who was the runner-up in ITV's I'm A Celebrity in 2008, vowed to fight her cancer, which was still in a very early stage with the same determination she had mustered to be the World No. 1 in tennis.

In January 2010, a routine mammogram revealed a lump in Navratilova's left breast, and she was asked to come back for a closer look.

Navratilova went back to have the lump magnified on February 23.

"They said, 'Well, there's a cluster, we will do a biopsy just to be sure'. So I went to Denver to get the biopsy. And they said it looks pretty good, it should be nothing," said Navratilova.

The tennis legend got a phone call from Dr Mindy Nagle at home in Aspen, Colorado on February 24, who said her that the report was positive.

"I'm like, 'Positive is good'. I was in denial for a couple of seconds and then I cried for, I don't know, a minute. OK, what do we do?" said Navratilova.

On March 15, the half-hour lumpectomy test was conducted on her, in which it was revealed that the cancer was not spread.

Navratilova, however, planned to keep it quiet.

"Nobody needs to know. But I went four years between mammograms. Another year and I could have been in trouble. I realised how many women put it off. I thought I'd use this to remind women to go for that check-up," she said.

A determined Navratilova, however, planned to compete in the French Open with Jana Novotna and began her six-week course of radiation on May 12.

But two weeks later, she did not feel any ill effects.

"They say you get tired maybe week four, five, six. I'm feeling nothing," Navratilova said.

Navratilova played the first match of the French Open on June 2, and won the French Open Legends on June 5.

The tennis star felt more tired climbing the stairs on June 9, and finally two days later, she had no energy left even for her usual practice.

"My worst day by far. I went to hit the ball, and I was so tired I lost it. I had to stop, I had no energy and it usually gets worse," she said.

The final day of treatment arrived on June 14, and three days after the treatment, Navratilova decided to be very careful in the near future.

"I'll be very meticulous now about going to the doctor and getting those six month check ups and one-year check ups. I'm not going to let that lapse again," she said.

Finally, with both physical and emotional energy back to normal, she along with Jana won the Ladies Invitation Doubles at Wimbledon on July 4.