The 19-year-old triple world record-holder clocked 4:08.41 seconds on the first day of the U.S. Olympic trials.
Michael Phelps won his sixth gold medal at the Beijing Games on Friday and then said he could prove to any doubters he is clean of drugs.
A fired up Michael Phelps signalled he was back in top form when he rocketed to a world record in the 100 metres butterfly at the U.S. Nationals on Thursday.
USA swimmer Michael Phelps wins men's 200-meter butterfly, his 20th Olympic gold.
For almost 20 years, Michael Phelps was swim coach Bob Bowman's project. But Phelps, who retired from swimming as the most decorated Olympian of all time after winning a record 22 medals including 18 golds, is now swing guru Hank Haney's project as he turns his sights on becoming a top golfer.
Ryan Lochte defeated Michael Phelps by more than a second in the 200 metres individual medley at the United States national championships on Friday with the year's best time of 1:54.84.
The American broke his own 200 metres individual medley world record taking .10 of a second off the previous record.
Michael Phelps said he is "not in the best shape" after finishing third in the short course 100 metres medley final at a World Cup meeting in Stockholm, on Tuesday.
Michael Phelps and powerhouse rowing teams from Australia and Britain were the early highlights at the Olympics on Monday when London's notoriously clogged roads appeared to handle the extra crush of traffic on the first business day of the games.
Michael Phelps opened defense of his Olympic title in the 200-meter butterfly with the fifth-fastest qualifying time in the preliminaries on Monday.
American swimmer Michael Phelps needed a little help from his friends on Monday to keep alive the dream of an unprecedented eight Olympic golds.
Michael Phelps shattered his own world record in the 400 meters individual medley final on Sunday in a devastating start to his campaign to collect eight Olympic gold medals in China. The lanky American fought off a strong challenge from Hungary's Laszlo Cseh and US team mate Ryan Lochte to win the gold in four minutes 03.84 seconds, wiping 1.41 off the world record of 4:05.25 he set at the US Olympic trials six weeks ago.
A flying visit to the Winter Olympics has provided Michael Phelps with fresh inspiration to stay ahead of his younger rivals in the build-up to the 2012 Summer Games in London.
Winner of 23 Olympic gold medals details his struggles with depression.
Michael Phelps swam into history with his 19th Olympic medal, and this one was a more appropriate color.
Ryan Lochte reaffirmed his status as the world's best all round swimmer when he beat Michael Phelps at the US Olympic swimming trials on Monday to book his spot on the American team for London.
Michael Phelps gifted himself an early birthday present by winning the 200 metres butterfly at the US Olympic swim trials on Wednesday to punch his ticket to the Rio Summer Games.
Ryan Lochte of the United States won the men's 200 metres freestyle title at the world swimming championships on Tuesday, beating Olympic champion Michael Phelps into second place.
Michael Phelps conquered Rome with a fifth gold medal in the men's 4x100 metres medley relay on Sunday when the American team closed an extraordinary world championships with a 43rd world record.
An Olympic historian disagrees with a widely held consensus that American swimmer Michael Phelps is the greatest ever Olympian.
Australia's long distance swimming champion Grant Hackett believes Michael Phelps' competitive streak could drive him to win a record eight gold medals at this year's Olympic Games in Beijing. Phelps is aiming to challenge the record seven gold medals American swimmer Mark Spitz won at a single Olympics -- in Munich in 1972.
Aaron Peirsol and Leisel Jones set world records to win their second gold medals at the world championships.
Michael Phelps and Allyson Felix were named as the United States Olympic Committee's (USOC) best athletes for 2011-12 on Monday for their gold-medal performances at the London Olympics.
Phelps, who has five golds and two bronzes, joined Mark Spitz as the only swimmers to win seven medals at a single Olympics.
Michael Phelps was back in familiar waters and on top of the winner's podium in his comeback to competitive swimming at the US Grand Prix in Charlotte on Friday.
Michael Phelps and Ryan Lochte both safely qualified for the semi-finals of the men's 200 metres individual medley at the London Olympics on Wednesday.
Michael Phelps barely qualified in the 400-meter individual medley on the opening day of Olympic swimming, squeaking into the final by seven-hundredths of a second on Saturday.
Ryan Lochte turned his much-anticipated duel with Michael Phelps into a blowout, pulling away to win the 400-meter individual medley by more than 3 seconds Saturday night. And even more stunning: Phelps didn't even win a medal.
American swimmer Michael Phelps became the most successful Olympian of all time when he won his 10th gold medal on Wednesday and his fourth of the Beijing Games. The mighty Phelps broke his own world record to continue his dominance in the Water Cube pool and overtake an elite group including Mark Spitz and Carl Lewis who had won nine golds.
Michael Phelps retained his 200 metres butterfly world title and smashed his own world record on Wednesday to reassert his authority after a tough 24 hours. The American lost his world record in Tuesday's 200 freestyle final when he was beaten by Germany's Paul Biedermann but he burst back to form with an awesome display of power.
A mischievous Michael Phelps hinted the Rio Games may not be his last. The most decorated Olympian of all-time said on Wednesday he is excited his infant son Boomer would be in the stands to watch "the potential" last races of his career.
Michael Phelps was jolted by a rare defeat and reminded of the work that lies ahead after he finished second to Aaron Peirsol in the 100 metres backstroke at the Charlotte Grand Prix on Saturday. Phelps, on only his second day of competition since his record eight gold medal haul at the Beijing Olympics, was well beaten to the wall, his time of 53.79 a far cry from Peirsol's 53.32.
Michael Phelps won the 18th gold of a mind-boggling career in the 4x100 metre medley relay on Saturday, retires with twice as many golds as any other Olympian.
The US swimmer will enter five individual events and three relays at the Athens Olympics in his quest to equal or surpass Mark Spitz's record haul of seven gold medals the 1972 Games in Munich.
Michael Phelps, the most decorated Olympian of all time with 18 gold medals among his career haul of 22, will carry the US flag in Friday's opening ceremony of the Rio Olympics.
Caeleb Dressel heads into the world championships in South Korea looking to show his rivals he is the man to beat at the 2020 Tokyo Olympics.
Michael Phelps turned the tables on his great rival Ryan Lochte to win the 200 metres freestyle final at the US Olympic trials on Wednesday and remain on course for another massive haul at the London Games.
Michael Phelps stakes his claim to be the ultimate Olympian on Wednesday, swimming two finals in an hour as he bids to overtake an elite group including Mark Spitz and Carl Lewis on a record nine career golds.