Luzhniki stadium

Britain's Mo Farah, right, crosses the finish line to win the men's 5000-meter final ahead of Ethiopia's Hagos Gebrhiwet, left, and Kenya's Isiah Kiplangat Koech, second from left, at the World Athletics Championships in the Luzhniki stadium in Moscow, Russia, Friday, Aug. 16, 2013. (AP Photo/Anja Niedringhaus)

Anja Niedringhaus/AP

Britain’s Mo Farah, right, crosses the finish line to win the men’s 5000-metre final ahead of Ethiopia’s Hagos Gebrhiwet, left, and Kenya’s Isiah Kiplangat Koech, second from left, at the World Athletics Championships in the Luzhniki Stadium in Moscow, Russia, on Friday. 

Bolt of Jamaica crosses the finish line ahead of Williams of Britain to win their men's 200 metres heat during the IAAF World Athletics Championships in Moscow

Fabrizio Bensch/Reuters

Usain Bolt of Jamaica (bottom) crosses the finish line ahead of Delanno Williams of Britain to win their men’s 200 metres heat during the IAAF World Athletics Championships at the Luzhniki stadium in Moscow, Russia, on Friday

Athletes compete in a women's 5000-meter heat at the World Athletics Championships in the Luzhniki stadium in Moscow, Russia, Wednesday, Aug. 14, 2013. (AP Photo/Martin Meissner)

Martin Meissner/AP

Athletes compete in a women’s 5,000m heat at the World Athletics Championships in the Luzhniki stadium in Moscow, Russia