MOTEGI, Japan - MotoGP champion Casey Stoner says he has recovered only 50% from injury but is ready to GP racing.The Australian will race in the 2012 Japanese GP on Sunday after missing the previous three events after injuring his right knee in a crash while qualifying at the Indianapolis GP in August 2012.The Honda rider's absence has meant it is now impossible for him to retain his crown, with the 2012 championship currently led by Yamaha ace Jorge Lorenzo, on 290 points and Stoner's team mate Dani Pedrosa second on 257.'ORDINARY PAIN-KILLERS'Stoner is third on 186 points with four races remaining. The winner of each race earns 25 points. In Friday's free practice he needed the help of painkillers as he clocked seventh-best while Pedrosa topped the times sheets.Stoner will start seventh on the grid on Sunday."I just needed ordinary pain-killers to take the edge off," he said. "I don't really like using painkillers because it wears off, especially when your body's circulating everything so quickly."About the progress of his recovery, Stoner said ahead of the practice: "Fifty percent, maybe. I expected my body to be up around 8% but it's not even close. I'm a little disappointed that we didn't make a little more progress.”Stoner underwent surgery on August 30 to repair torn ligaments and fractures to his ankle, tibia and fibula at Indianapolis, although he still lined up for the race and finished fourth."To be honest, I expected more (progress) but the doctors didn't. The doctors warned me that it was going to be six to eight months before we know it's acceptable," said the 2007 and 2011 World champion who will be 27 on Tuesday."It's only two months so I'm a little bit greedy," he said.'COULD BE... LIFE-CHANGING'He had intended to make his return to racing at his home GP at Phillip Island on October 28 but instead opted for an early comeback at Honda's home track.Asked if he had thought about the health risks involved, he said: "If I crash again and injure the same foot, then the injury could be, you know, life-changing... for a while, anyway."Honestly, probably, I shouldn't be back here," Stoner admitted, “but I was not going to miss Phillip Island in my last season. For me to at least get back the speed before I get there is better."Three races will be fought over three weeks in Japan, Malaysia and Australia before the season finale in Valencia, Spain, on November 11.Stoner admitted his injured foot still needed to be extensively treated with all his ligaments stretched or torn. After Saturday’s free practice, around right-hand corners, he said, "I couldn't flex my foot far enough to get my weight forward on the bike."I was just trying to get my foot to move a little bit more but it seemed stubborn.”Stoner said it was in his nature to race to win. While Lorenzo has won four races in total, Pedrosa was victorious in three of the previous four events. Stoner won the other four before he was injured."When you come back after a while, especially when you've been so competitive, it ends up more frustrating (if) you can't get the place where you wanted to be."