It was ecstasy and then agony for Olympic champ Phelps

As the Olympic champion swimmer failed to qualify for 400m freestyle final

Olympic swimming champion Michael Phelps suffered his first setback in his return to the pool after he failed to qualify for the 400 metres freestyle final in Mesa, Arizona on Friday.

Phelps, competing first time following a six-month ban for a drunk driving conviction, flashed his old form on Thursday when he won the 100 metres butterfly in the Arena Pro Swim Series meet.

But on Friday, the 18-times Olympic gold medalist could only manage 17th in the 400 freestyle after a time of 4 minutes, 2.67 seconds kept him out of the main final.

Phelps' time put him in the C final but he elected not to swim it and also pulled out of his scheduled 100 metres backstroke race in the evening.

While it was not the result he was looking for, Phelps was swimming the freestyle for the first time since 2009 and said he saw it as a personal challenge.

He spent the rest of the evening working in the television booth as he will now turn his attention to Saturday's 200 individual medley and 100 freestyle events.

Phelps is competing for the first time since last August with an eye toward returning to glory at the 2016 Olympic Games in Rio.

Whereas Britain's Peaty sets 100 metres breaststroke world record

Britain's Adam Peaty smashed the world record for the 100 metres breaststroke at the British swimming championships.

The 20-year-old, who also holds the 50m world record and won European and Commonwealth titles last year, finished in 57.92 seconds, beating the 58.46 mark set by South Africa's Cameron van der Burgh on his way to Olympic gold at London 2012.

"I kind of surprised myself," Peaty told the BBC after becoming the first man to break the 58 seconds barrier.

"I was going to wait until Kazan (world championships) to produce that time and I can't really believe it.

“The crowd really carried me home on the last 50 because it’s a hell of a pain train. It’s kind of surreal, there must be something in that lane four that really matters.

“I knew I could get 58 mid and I knew that if the heavens were on my side I could get a 58 low but to be the first person under 58 -- I have got no words.”