Jelena Jankovic considered retiring due to a bad back toward the end of last fall and early winter, she told

The former No. 1 said she sat in her bed for two months, barely standing up, and said the pain was so bad that she thought her tennis career was over.

"I thought this maybe could be the end of my career,” Jankovic said in Brisbane after she lost to Ajla Tomljanovic, 7-6 (6), 6-0. “It was really bad. Not sick. Just when you are injured and you have a bad back injury, you're thinking maybe you're never going to be able to play again at a high level. Just kept doing therapies. I was just trying to recover. And I did. But there is still something in the back of my mind. Sometimes when I play I'm a little bit tense where I just don't want to get there again.”

The 28-year-old last played in October in Tianjin, where she lost in the second round. Currently ranked No. 15, the Serb did not reach a tournament semifinal after Rome, in May. She did manage to reach the fourth round of the U.S. Open, but lost to Swiss teenager Belinda Bencic.

“I lost my muscles and I look like jelly,” Jankovic said. “There was nothing there. Then when I saw myself in the mirror a month ago I was like, ‘Oh, my God. I got to do some work,’ so I think I've improved a lot.

"With that all said, I still need to do a lot of work to get where I want to be. Because of that injury, I needed more time to recover and heal, because it was a bad injury.

"It can be tough on you just overall on the mental aspect where you cannot even brush your teeth properly. You have to find a technique to bend down. You kind of get down. You don't feel happy where you cannot do normal daily activities, such as brushing your teeth; putting my shoes on was a tough task for me. So it took a while to get better and to kind of heal.”