Reigning 100 meter and 200 meter Olympic champion Usain Bolt says he is surprised that rival Justin Gatlin failed to advance to the 200-meter final on Thursday.
"Everybody's in shock," Bolt told BBC Radio 5 Live. "You can tell from the 100 meters he's getting old. It's a fact the older you get, the rougher it gets to double."
Gatlin, 34, and a silver medalist in the 100 meters, finished third in his 200-meter heat.
Bolt will look to defend his title and won his semifinal heat in 19.78, 0.02 seconds faster than Canadian sprinter Andre De Grasse.