London 2012 Olympics: Day One's must-see moments
Who will come out on top between 14-time gold medal winner Michael Phelps and world champion Ryan Lochte as the American swimming rivals go head to head?
Here are Saturday's events to watch out for (all times BST):
Read up on the protagonists:
- SWIMMING (19:30-20:58):
- Men's and Women's 400m Ind Medley, Men's 400m Freestyle, Women's 4x100m Freestyle Relay
Michael Phelps has 14 Olympic gold medals to his name already and will look to add to that collection after enduring a nervous qualification for the final of the 400m individual medley. He will face stiff competition from his compatriot and world champion, Ryan Lochte.
In the equivalent women's event, Hannah Miley has a chance to secure a medal for Great Britain, as do the 4x100 freestyle relay team of Rebecca Turner, Amy Smith, Jess Lloyd and Caitlin McClatchey.
- WOMEN'S FOOTBALL (17:15-19:00):
- First Round Group E Match 2
In their second match of the Games, Great Britain play Cameroon at the Millennium Stadium in Cardiff, with victory and qualification for the next stage firmly in their thoughts.
- WOMEN'S HANDBALL (19:30-21:00):
- Preliminary Round Group A Match 5
Montenegro are the opponents for Great Britain at the Copper Box, followed by the Group B game between Norway and France.
- WOMEN'S BASKETBALL (22:15-23:59):
- Group B Game 6
Great Britain take on Australia in the preliminary round. GB player of the year Julie Page has called on the team to show strong unity when they take on the Australians, who won silver at Beijing.