Michael Phelps dives into the Olympic pool on Saturday in search of the first of a possible record eight gold medals as the Athens Games explode into life.

Appropriately the first event for the 19-year-old American is the 400 metres individual medley, showcasing each of the four strokes with which Phelps will attempt to better Mark Spitz's haul of seven golds at the 1972 Munich Games.

Phelps has also entered the 200 individual medley, the 100 and 200 metres butterfly and the 200 freestyle. He is a candidate for three of the relays.

Australia's Ian Thorpe, who takes part in the 400 freestyle, also has a Spitz record in his sights.

Thorpe, who won three gold medals at the 2000 Sydney Games, has targeted six titles in Athens which would equal Spitz's tally of nine in two Olympics.

The Australian is the man most likely to thwart Phelps's ambitions.

He is projected to meet Phelps in Monday's 200 freestyle final, which also features defending champion Pieter van den Hoogenband and former world record holder Grant Hackett.

Thirteen Olympic titles will be decided on Saturday, including four in the swimming which commands centre stage until the athletics programme starts in a week's time.

The most dramatic event on Saturday promises to be the men's cycling road race which takes the field under the Acropolis and up the Lycabettus hill which was once crowned by a statue of Zeus.

Race favourite Jan Ullrich of Germany needs two medals in Athens to become the first man in the 108-year history of Olympic cycling to win four gold medals on the road.

Ullrich will have an extra incentive to win after a disappointing performance in the Tour de France this year.

He finished fourth behind six-times champion Lance Armstrong, the first time he has failed to make the podium in seven years. The race comprises 17 laps of a 13.2-km course.