The showdown we've been waiting for is finally here.
Usain Bolt, Justin Gatlin, and the rest of the biggest names in men's track completed their semifinal heats for the coveted 100-meter dash Sunday evening. Amidst accusations of doping, Gatlin finished first in his heat and will advance to the finals.

Amongst concerns about injury, Usain Bolt, the two-time defending champion in both the 100-meter and 200-meter and fastest man ever timed, came in first in his heat as well. With his race, he seemed to have answer the questions regarding his health and laid down the gauntlet against Gatlin for the final.

While both runners dominated their respective heats, Bolt finished with a faster time and a more dominating fashion. Fans took to Twitter to react to the semifinal results. 

The final race will take place later this evening. It will be fascinating to see if Bolt can defend his historic dominance of the sport and achieve the unheard of triple-crown, or if Gatlin can find redemption and achieve the success he has sought after for so long, or if a new name will be crowned king of Olympic track.

While there are many more men racing for Olympic gold tonight, it still looks like a two-man race between Bolt, and Gatlin.