Michael Phelps has posted a time of 1min 45.69sec in the 200m freestyle event at the USA Swimming event in Columbus - the second-fastest of the year.

Michael Phelps posted the second-fastest 200m freestyle time in the world this year on Friday, signalling that his preparations for the London Olympics are on track.

"It's crazy what training actually does," Phelps said with a laugh after he cruised to victory at USA Swimming's Columbus Grand Prix in 1min 45.69sec.

"When you do start to train, and you do start working out, you do get in better shape. It's kind of wild how that works."

Phelps's time is second this year only to the 1:45.52 delivered by France's Yannick Agnel.

Germany's Dimitri Colupaev was second in 1:48.70 and Brazil's Nicolas Oliveira was third in 1:49.99.

Phelps, whose 14 Olympic gold medals include an unprecedented eight in one Games in Beijing in 2008, was competing for the first time since spending three weeks training at altitude in Colorado.

The US superstar, who has admitted he lost motivation and focus after his Beijing triumph, was pleased not only with the time but with his race execution.

"I said I wanted to be out in 51 and just kind of feel like I have control over my speed," Phelps said.

"That's kind of how it was. I felt kind of like the old me."

Phelps is slated to swim in the 200m butterfly on Saturday and the 100m free and 200m backstroke on Sunday.

US Olympic gold medallist Natalie Coughlin was also a winner on the night, capturing the 100m butterfly in 59.17 - tied for seventh-fastest in the world this year.

International swimmers prepping for a run at the London Games also featured strongly on the opening night of the meeting

Japan's Kosuke Kitajima won the men's 100m breaststroke in a meet record of 1:00.13, not far off his time in the heats of 1:00.98.

Slovenia's Damir Dugonjic swam strongly for silver in 1:00.60.

David Verraszto and ZsuZsanna Jakabos gave Hungary a medley double, winning the men's and women's 400m races.