American sprint star Fred Kerley said it was "on and popping" ahead of his much-anticipated showdown with Olympic champion Marcell Jacobs after opening his 100m season in Japan on Sunday.

Kerley clocked 9.88sec in his heat at the Seiko Golden Grand Prix in Yokohama before winning the final in 9.91, following two false starts from his rivals.

The 28-year-old Texan will square off over 100m against Jacobs -- who he has not faced since the Italian beat him to the gold at the Tokyo Games -- in Diamond League meets in Rabat on May 28 and Florence on June 2.

Kerley is looking to defend his 100m world title in Budapest in August and said he was "up for any challenge" as he trained his sights on Jacobs.

"Track and field is a competitive sport, so any given day we can compete against the top guys in the world is a wonderful feeling," said Kerley.

"Hopefully he don't duck out of this race. I'm in Morocco tomorrow so it's on and popping."

Kerley's time in his heat was his fastest 100m season-opener, and also a meet record.

He is aiming for a 100m-200m world double in Budapest and said he was "the fastest man in the world, no doubt about it".

- Sprint double -

He called Jacobs a good friend off the track but said "competitively, I hate the ... out of him".

"My main rival is myself," said Kerley.

"No disrespect to another athlete -- I can easily get myself mentally out of a race. I think my own rivalry is in between my own ears and my own brain."

Kerley opened his Diamond League season with a 200m win in Doha earlier this month, clocking 19.92sec to finish ahead of fellow American Kenneth Bednarek.

He will race against reigning 200m world champion Noah Lyles at that distance in next month's New York Grand Prix.

Kerley said he was "confident in both" the 100m and 200m as he looks to claim the first men's sprint world double since Usain Bolt in 2015.

"I'm confident every time I step on the track," said Kerley.

"I don't like to be second best to nobody. No disrespect, I expect to win every time I step onto the track."

He already has his sights set on next year's Paris Olympics, where he intends to go one better than his silver from the Tokyo Games.

"The only thing I want out of Paris is a gold medal, an individual gold medal," said Kerley.

"I came up 0.04 short and I don't plan on coming up short this time."

amk/pbt