I can say, without a doubt, that for me, the most exciting moment of the 2012 London Olympic Games was the final 3 laps of the Men's 10,000 meters final.
As the final laps of the race began, Alberto Salazar's protege, Galen Rupp, a 26 year old American was still hanging in with the older, more experienced, Kenyan and Ethiopian runners. Rupp patiently held his position in the middle of the lead pack for another 2.5 laps; and then, with 200 meters left in the race, he unleashed a perfectly timed finishing kick and surged past everyone except his friend and training partner Mo Farah. Farah won the gold medal and Rupp won the silver medal.
Rupp's silver medal was the first medal won by an American in the 10,000 meters in 48 years. The moment that Galen Rupp crossed the finish line in second place, he instantly changed the dialogue about the ability of a native born American runner being able to compete against the best distance runners in the World. For the first time in decades, the future of American distance running looked bright.
Unfortunately, the hope of a bright future that Galen Rupp brought to American distance running began to dim all to soon. On June 3rd, 2015 a report surfaced that accused Alberto Salazar of giving the runners that he coached, including Galen Rupp, performance enhancing drugs.