London 2012 is underway through Aug. 12, with more than 10,000 athletes from 204 counties competing in 26 sports. Many events will air live on NBC networks (see full TV listings here), and 3,500 hours will be stream lived on NBCOlympics.com. Here's what to watch at 8 p.m. ET/PT on NBC on Saturday, July 28:
The big event: The men's 400m individual medley relay, a grueling four-part race of essentially all-out sprints of four strokes: butterfly, backstroke, breaststroke and freestyle.
The stars: Much has been made of the American teammates' Michael Phelps’ and Ryan Lochte's rivalry, and this race will be the first of potentially six face-offs. Lochte is the reigning world champion in the event and beat Phelps in a head-to-head victory at the Olympic trials. But Phelps holds an astounding 14 medals – including two golds in this event – to Lochte's six and is certainly capable of winning here, too. Expect a close finish.
When: Qualifying heats will be held at 5 a.m. ET at the stunning London 2012 Aquatics Centre. The medal races will take place at 2:30 p.m. ET. The medal races will air during NBC's prime-time show at 8 p.m. ET/PT.
What else to watch: The men's 400m IM is just one of four gold medal swimming finals Saturday, including the same race for women, the men's 400m freestyle and the women's freestyle relay.
Also showing on the prime-time replay will be men's gymnastics qualifying rounds. China has dominated the sport, but Japan, powered by Kohei Uchimura, who hasn’t lost an international competition since 2008 in Beijing, is a rising power. There are also high hopes for Team USA.
Beach volleyball at the Horse Guards Parade, located on the Prime Minister’s doorstep in central London, also gets going.
More details on what to watch Saturday can be found at NBCOlympics.com.
For a full local listing of events being shown all day on NBC, the NBC Sports Network, Bravo, CNBC, MSNBC, the NBC Olympic Soccer Channel, the NBC Basketball Channel and Telemundo, please see your local TV listings section of NBCOlympics.com.