Allyson Felix feels she is close to being back to her best after an ankle injury led to disappointment at the United States Olympic team trials in July.
Felix was set to compete in the 400 and 200 metres at Rio 2016, but failed to qualify in the latter event after finishing fourth in the U.S. trials.
The 30-year-old will consequently be unable to defend the 200m gold she won in London four years ago when she takes part in her fourth Games in Brazil.
However, the American is confident in her condition ahead of an attempt to add to her six previous Olympic medals.
"I feel like I've made progress since the trials, I feel better than I did at trials," said Felix.
"Trials are so demanding, physically and emotionally, it was rough on me this time. I have some issues with recovery, but they are under control. I feel normal, close to my best.
"Each time [at the Games] it's a different experience. I've had a lot of adversity this year. I'm happy to try and get it done. I'm going after a new challenge."
Felix was part of USA's 4x100m and 4x400m relay-winning teams at London 2012 and is looking forward to renewing their rivalry with Jamaica, who had to settle for silver and bronze respectively.
"It's a highlight for us. We bring out the best in each other. It will be another great showdown," she said.