Michael Phelps will be chasing history at the 2008 Beijing Games as he tries to break Mark Spitz's record of winning seven gold medals at a single Olympics.

But Phelps, who won eight medals -- including six golds -- at the 2004 Athens Games, will be challenged by some of the world's top swimmers, including some of his own American teammates, on his quest for history.

Meet the men who could ruin Phelps' bid for perfection in the individual events at the 2008 Olympics.

Ian Crocker, United States, 100m Butterfly
Phelps' top challenger in the 100m butterfly is expected to be the Baltimore native's compatriot, Ian Crocker. Crocker is the world-record holder in the event, but Phelps has bested him head-to-head as of late. Phelps, the defending Olympic gold medalist in the event, topped Crocker at the 2007 World Championships and the U.S. Olympic swimming trials. However, while Phelps is slated for a busy Beijing schedule, the 100m fly will be Crocker's only individual event at the games.

Pieter van den Hoogenband, the Netherlands, 200m Freestyle
The 200m freestyle was the only individual Olympic event that Phelps entered and did not win at the 2004 Athens Games. The American finished third in Athens behind the now retired Ian Thorpe of Australia and the Netherlands' Pieter van den Hoogenband. Phelps and van den Hoogenband duked it out again at the 2007 World Championships, where Phelps took gold and the Dutch swimmer settled for silver.

Wu Peng, China, 200m Butterfly
Phelps could be tested by China's Wu in the 200m butterfly. Wu, who is regarded as China's top male swimmer, finished second to Phelps at the 2007 World Championships. Taking the gold from Phelps could be a tall order for Wu, as Phelps is the world-record holder and reigning Olympic champion in the event.

Ryan Lochte, United States, 200m and 400m Individual Medley
American Ryan Lochte could be Phelps' biggest threat in the 200m and 400m individual medleys. The Florida native has pushed Phelps in the two events, but has struggled to finish ahead of him. Lochte finished second to Phelps in the 200m IM and 400m IM at the U.S. Olympic trials, where Phelps set world records in both events. Lochte also finished second to Phelps in the 200m IM at the 2004 Athens Games, and took silver in the 200 and 400 at the 2007 World Championships.