Omaha - Michael Phelps's bid to maintain Olympic swimming supremacy begins in earnest next week, when he renews his rivalry with Ryan Lochte at the US Olympic swimming trials.
Both are entered in the 400m individual medley on the opening day of the trials on Monday.
The demanding event was among Phelps's unprecedented eight victories in one Games at Beijing four years ago - after which he said he would never swim it again in competition.
However, Phelps is still the world record-holder, and has waffled on that stance this season.
Lochte, who put his name down for 11 events, is entered in all seven that Phelps has entered. It's more than likely, however, that neither will swim all the events he has entered during the eight-day trials.
Phelps and Lochte are also both entered in the 100m and 200m freestyle, the 100m and 200m butterfly, the 200m backstroke and the 200m medley.
Lochte set the 200m medley world record at the world championships in Shanghai last year, the first men's long course world mark since high-tech bodysuits were banned.
He's seeded number one, ahead of Phelps, in both medleys. Phelps goes into the 100m and 200m butterfly as the top seed.
In Beijing, Phelps won the 100m and 200m butterfly, the 200m and 400m medley, the 200m freestyle and three relay golds.
In the Olympic trials that year, which were also held in a temporary pool at Omaha's Qwest Center arena, he was originally entered nine events but eventually completed - and won - five.
Phelps has been cagey about his plans for the London Olympics, which he says will be his last.
However, he and longtime coach Bob Bowman have indicated he won't try to emulate his eight-gold feat of Beijing,
Phelps owns a total of 16 Olympic medals, 14 of them gold. With a multiple medal performance in London, he could surpass Soviet gymnast Larisa Latynina as the winner of most career Olympic medals. She won 18 medals, including nine golds, from 1956-64.