Usain Bolt says he'll definitely be nervous when he makes his first appearance for A-League club Central Coast Mariners in a pre-season practice match on Friday night.

The Olympic track great has been training on the left wing since beginning his trial with the club last week and says he hopes to play about 15-20 minutes against a Central Coast amateur selection in Gosford.

Mariners officials are predicting a crowd of about 12,000.

While Bolt has performed in front of far bigger crowds and on much grander stages, he expects to feel some butterflies.