Michael Phelps delivered a blistering 200m butterfly time of 1:55.32 on Saturday, clocking the fastest time in the world this year to win the event at USA Swimming’s Columbus Grand Prix in Ohio.

Phelps improved on Joseph Roebuck’s 1:55.94 set at Britain’s Olympic trials at London’s Olympic Aquatics Centre last Tuesday.

He sliced more than half a second off that time, gaining a comfortable victory over Tom Kremer (1:58.34) and Dakota Hodgson (1:59.31).

Japan’s Kosuke Kitajima won the men’s 200m breaststroke in 2:10.35, good enough for fourth on this year’s world list.

Masayuki Kishida grabbed another victory for Japan, winning the men’s 50m freestyle in 22.62 ahead of South African Graeme Moore (22.75) and Hungary’s Krisztian Takacs (22.78).

Hungary’s Zsuzsanna Jakabos cruised to victory in the women’s 200m fly in a time of 2:08.09, which put her sixth in the world this year.

Natalie Coughlin won the women’s 100m backstroke in 1:00.81, with Mexico’s Maria Gonzalez Ramirez second in 1:00.96.

Phelps had plenty of energy left over to sign autographs for eager swim fans.

He said it’s all part of his long-time goal of raising the profile of swimming in the United States.

“It’s awesome that if you would have had this meet eight years ago you wouldn’t have had half this many people here,” Phelps said.

“There are a ton of people who are out here supporting us. That’s something that is amazing. People are excited to come out and watch us swim. “