Usain Bolt ran a season's best 100metre time of 9.98 seconds to win at the World Challenge League meeting in Ostrava, but acknowledged more work is needed.

The Jamaican started slowly, but picked up the pace to surge to a comfortable victory in the Czech Republic, beating Barbados' Ramon Gittens by 0.23secs.

Despite not being close to his 100m world record of 9.58secs, Bolt improved upon his previous quickest run this season of 10.05secs.

The six-time Olympic gold medalist is confident improvement can be made ahead of Rio 2016.

"The power behind the start wasn't there. I didn't execute," said Bolt.

"I had to get to work a little bit harder at the end to get up the speed.

"If I can improve that it should be okay. This is a very important season. This is a very big year for me."