ROME, ITALY - MAY 31: Jamaica's Olympic 100m champion Usain Bolt reacts after winning the 100m men at the IAAF Compeed Golden Gala at Stadio Olimpico on May 31, 2012 in Rome, Italy. (Photo by Paolo Bruno/Getty Images)
The 2012 Summer Olympics begin Friday in London, and Matt Ufford and Amy K. Nelson preview 10 international athletes or teams to watch.
There are 10,490 athletes from 204 countries competing in the 2012 Summer Olympics. Most will come to London, compete and leave without gaining national or international attention.
While many of the Unites States' top athletes are well known, there are plenty of athletes from other countries worth watching in London. SB Nation's Amy K. Nelson and Matt Ufford preview 10 international athletes or teams to watch in the 2012 Summer Olympics.
Roger Federer and Usain Bolt are likely the two most notable names on the list, but they are far from the only interesting international athletes to watch. The 2012 Summer Olympics will also feature the second oldest Olympian ever, when 71-year-old Hiroshi Hoketsu competes in dressage.
The list also includes two teams who could pose significant challenges for their American counterparts. Spain's men's national basketball team is considered the top challenger to Team USA, while Brazil's women's national soccer team has a long history against the United States.