Retired sprint Usain Bolt says he is struggling with the tempo of professional football but is working hard to raise his fitness levels ahead of his first trial match this week.

The eight-time Olympic champion has been given an opportunity by Australian A-League club Central Coast Mariners to earn a professional contract and has stepped up his training regimen since joining up with the team last week.

Bolt, who is set to play for the first time on Friday when they take on a team of local amateurs, was put through his paces with the rest of the squad at a more intensive session at the team’s base in the town of Gosford, 75 kilometres north of Sydney.

After some warming up and a jog around the pitch, he took part in ball drills and while his passing was fine, he was slow to get the hang of the movement required.

The 32-year-old’s lack of football fitness was also evident and he appeared to tire quickly, resting more than his teammates.

He admitted to struggling with the constant stop-start of football, more used to a quick fire sprint on the athletics track before winding down.

“The most challenging thing for me is the stop and go because I’m not used to picking up speed, going back down, then back again,” he said.

“It’s all about practising and getting used to the system. I have time so will just learn the ways and keep pushing.”

There were some positives though as Bolt said he was seeing slow improvements in his game.

“For me it’s about just getting fit and as many touches of the ball that I can. The more I play the more comfortable I get,” he said.

“It’s all about being focused, taking my time and being smart and pushing myself to get to the level I need to be at to be in the starting XI.”