Day 15: What to Watch For

Here are some of the events, teams and athletes to watch Friday at the London Games. (All times Eastern.)

TRACK AND FIELD It might be hard for the men’s 4×400 relay final (nbcolympics.com, 4:20 p.m.) to surpass the drama of the heats, where the American Manteo Mitchell broke a leg during his team’s qualifying run, and Oscar Pistorius’s South African team crashed and then was reinstated on appeal. The Bahamas and the United States tied for the fastest qualifying times. The women’s 4×100 relay (nbcolympics.com, 3:40 p.m.) will be the latest duel between United States and Jamaica, though neither team earned a medal four years ago because of bad hand-offs. Other finals Friday include the men’s pole vault, the women’s hammer, the women’s 1,500 meters and the women’s 5,000 meters, where Tirunesh Dibaba is attempting to add to her gold in the 10,000. She won both events in Beijing four years ago. NBC, 8 p.m. (taped)

BASKETBALL The men’s basketball semifinals are rematches of games just a few days ago. The United States meets Argentina (NBCSN, 4 p.m.), whom the Americans beat, 126-97, in a contentious game Monday. The teams are playing the semifinals for the three consecutive Olympics. The previous meeting between Russia and Spain was closer, with the Russians winning, 77-74. Spain led by 9 with four and a half minutes left before Russia rallied. Russia has not won an Olympic basketball medal since 1988, the last Games that did not include N.B.A. players. NBCSN, Noon

SWIMMING The men’s 10,000-meter swim takes place at Hyde Park in the lake called the Serpentine, though the locals are fond of referring to it as the Turpentine for its murky appearance. Ous Mellouli of Tunisia, who won a bronze medal at the pool in 1,500-meter freestyle, will be the first swimmer to compete in both a pool and an open-water event at the same Olympics. Alex Meyer leads the American team, swimming in the memory of his friend, Fran Crippen, a top open-water swimmer who died during a race in 2010. nbcolympics.com, 7 a.m. NBC, 12:15 p.m. (taped)

SYNCHRONIZED SWIMMING Russia has won the team event for three consecutive Olympics and scored 98.1 out of a possible 100 points in its technical routine. nbcolympics.com, 10 a.m. NBC, 12:30 p.m. (taped)

TAEKWONDO Diana Lopez,a bronze medalist in Beijing, failed to medal Thursday, but her brother Steven, a two-time Olympic champion, fights Friday in the under-80-kilogram division. The Lopez family, including brother Mark, has earned at least one medal at each of the previous three Game. Steven Lopez has a difficult draw, opening against the No. 1 seed, Ramin Azizov of Azerbaijan. nbcolympics.com, 4:15 a.m.; NBCSN, 8 a.m.