Former 100 metres world record holder Asafa Powell ran an impressive 9.96 seconds on his return to competition from a shoulder injury at the Trinidad national championships on Saturday.

The race, into a slight head wind with persistent drizzle, was the Jamaican sprinter's first since February.

"I was a bit nervous about the conditions," Powell told Reuters. "With the rain and also the fact that it was my first race back from injury."

He ran as a guest in the semi-finals in Trinidad but chose not to compete in the final, saving his energy for next weekend's showdown with world record holder Usain Bolt in the Jamaican national championships and Olympic trials in Kingston.

Powell started slowly behind Trinidad's Richard Thompson but caught his younger rival before the halfway mark and glided to the finish. Thompson, the U.S. collegiate champion, was second in 10.11 seconds.

It was 25-year-old Powell's 34th career sub-10 second performance and equalled the sixth-fastest time of the year.

Powell injured his right shoulder while lifting weights in April.

Countryman Bolt has since taken the world record with a stunning run of 9.72 seconds in New York. Powell's previous record was 9.74 seconds set in 2007.