Rome - Usain Bolt is "slightly nervous" for the first time in his career.
The 100m world record holder will make his season debut in Thursday's Golden Gala meet, his first race since getting beat by Tyson Gay in Stockholm last August to end his two-year unbeaten streak.
Bolt said the loss to Gay changed "absolutely nothing."
"You lose some and you win some. You never win every race in your entire career. Last season wasn't my best season. It was kind of my season downtime for me," the Jamaican said. "This season is back to business. I want to prove to the world that I'm still the best."
After the loss to Gay, Bolt ended last season early due to back and Achilles' tendon problems.
"For the first time I'm slightly nervous - I haven't run in so long," Bolt said. "I'm always calm and relaxed. As I said I'm a little bit nervous, but I know I'm getting in shape. Me and my coach have done a lot of work leading up to this race."
Bolt recently got approval to race again from a physician in Munich.
"The doctor gave me the go ahead," he said. "I wouldn't say I'm in perfect shape but good shape, so I'm looking forward to competing."
Since he last raced, Bolt has added more muscle to his frame, rolling up the sleeve of his shirt and pointing to his flexed biceps at one point to demonstrate the fact during a packed news conference Tuesday.
"I've been doing a lot of work strength-wise, core-wise, that's why I may look a little different," he said, noting that he needs to improve his starts. "What has really bothered me over the years is the first 30 meters, because I'm tall. I've been working on it."
Bolt will face fellow Jamaican and former world record holder Asafa Powell, as well as European champion Christophe Lemaitre at the Stadio Olimpico.
Bolt is also planning to race in Ostrava and Oslo as he warms up for the August 27-September 4 world championships in Daegu, South Korea.
"I'm not really expecting anything, I'm just going out there to see where I'm at and see what I need to do for the world championships," he said. "These meets are stepping stones for the world championships. My whole focus this year is just to work toward the world championships."