( CNN ) -- The United States has injury worries on the track while the basketball team worries about a familiar foe . Here are five things to watch at the Olympics on Friday : . 1 ) Men 's 4x400 relay : U.S. hopes to continue streak . The United States is lucky to be in the final , lucky , that is , that Manteo Mitchell found a way to finish his opening leg despite a broken fibula . The United States will have to find a replacement for him as they challenge the Bahamas for the gold . Also keep an eye on Great Britain , which will have most of the 80,000 fans at Olympic Stadium cheering for them . Why Olympians bite their medals . Final is at 9:20 p.m. London time ( 4:20 p.m . ET ) 2 ) Basketball : U.S. dreaming of another final . Team USA faces veteran Argentina in what could be a tough semifinal matchup for the dominant Americans . Sure the United States beat them 126-97 in the preliminary round , but it was a one-point game at half and surely the Americans wo n't score 42 points in the third quarter again . Argentina figures to slow the game down a little and they are expected to have point guard Pablo Prigioni back . London 2012 : Live blog . Semifinal game begins at 9 p.m. London time ( 4 p.m . ET ) . 3 ) Cycling : BMX , baby . Eight riders , lots of jumps and bumps , some sharp turns , lots of crashes . As the New York Times said : `` Given the carnage on display Thursday , it is safe to assume that whoever designed the BMX racetrack really dislikes BMX racers . '' Both men and women compete in the event with semifinals and final on Friday . Soccer : U.S. women beat Japan . The first events begins at 3 p.m. London time ( 10 a.m . ET ) 4 ) Boxing : Superheavyweight super fight . Defending superheavyweight champ Roberto Cammarelle takes on world No . 1 Magomedrasul Medzhidov . Cammarelle , from Italy , is one of only eight boxers to win three medals ( he is already guaranteed at least a bronze . ) Like his opponent , Medzhidov is on the shorter side for the weight class , but he makes up for a usual reach disadvantage with a powerful punch . Swim coach : Australia getting 'soft ' Boxing begins at 1:30 London time ( 8:30 a.m . ET ) . Superheavyweight matches begin at 10:30 p.m. London time ( 5:30 p.m . ET ) 5 ) Women 's 4x100 meter relay : Chance at redemption . Running with two backups , the United States came within a hair of breaking the Olympic record . On Friday , Carmelita Jeter and Allyson Felix will be back in the lineup for the Americans in their matchup against Jamaica . It is unclear if Jeneba Tarmoh , Tianna Madison or Bianca Knight will run again . Each team is looking for redemption as both teams botched handoffs at Beijing . Genocide survivor leads way for Rwandan athletes . Round 1 of the relays begins at 8:40 p.m. London time ( 3:40 p.m . ET )
The U.S. relay team has three injured runners . A runner is carried off the track after being hit by a car during practice for the men's 4x100m relay. BMX racing has been crash-filled at London . U.S. women 's sprint relay teams are looking to make up for bad races in 2008 .