Eight-time Olympic champion, spring king Usain Bolt wants to be a footballer, and is all set to take the field for the Central Coast Mariners in an Australian A-League pre-season exhibition game. He, however, is finding it hard to keep pace with the level of fitness required.

Bolt went through the drills that the rest of his team went through. This included warming up, a jog around the pitch, ball drills and passing.

However, the 32-year-old was seen getting exhausted quicker than his teammates. He was looking to play at the left-wing and was hoping to play 15-20 minutes in that position.

"There definitely will be nerves, it's not like it's a charity game anymore," Bolt told Associated Press. "I expect to make mistakes but I also expect to go out there, make myself proud and to push myself.

Bolt had his first full practice session with the Mariners on Tuesday after taking time to ease into his new role during his first week with the club. He appeared at times to struggle with the pace and demands of training.

Some critics have said Bolt's bid to turn professional is little more than a gimmick, but the staff at the club say they're giving the world's fastest runner a chance to prove himself.

"The thing he's struggling with more than anything else right now is getting used to the football fitness," Mariners coach Mike Mulvey said. He said in terms of skills, Bolt is "doing OK."

"He's got rudimentary skills, there's no problem about that," Mulvey said. "It's about being able to do it at the speed that we do it."

Bolt said he's finding the nature of football training different and demanding but felt he had made some improvement in his first week.

"For me, it's the stop and go's, the tick-tacks. Because I'm not used to picking up speed, going back down, up and down, up and down, back and forth, that's the most challenging," he said. "The season doesn't start until the end of October, so I have time."

The 32-year-old Bolt, who holds the world records for the 100- and 200-meter sprints and was the undisputed track and field star of three Olympics, thinks he isn't far from full fitness.

"It's just time," he said. "I don't know how my body is going to feel. I know when I'm on the field I'm always going to push myself."

(With agency inputs)