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RIO DE JANEIRO — Usain Bolt had to work harder than he wanted in order to win his semifinal heat in the 200 meters Wednesday night.

Canadian phenom Andre De Grasse sprinted through the finish line instead of taking his foot off the gas late in the race to save energy for Thursday’s final.

Bolt decelerated once he thought he had the race won at 150 meters only to speed up again when it became clear De Grasse would beat him otherwise. The Jamaican superstar crossed the finish line in 19.78 seconds, a huge grin on his face and right index finger wagging in the air as if to chide De Grasse for having the audacity to challenge him.

“I wanted to take it easy, but he had other ideas,” Bolt said with a smile. “He decided that he wanted to run fast and I saw that he got a national record out of it. So he means business.”

Usain Bolt smiles at Andre De Grasse (L) after the 200-meter semifinal Thursday. (Getty) More

De Grasse’s time of 19.80 seconds indeed set a new Canadian record. The 21-year-old 100-meter bronze medalist has established himself as a future sprinting star in a sport that will lose Bolt, Justin Gatlin and a handful of other big names before to the 2020 Olympics.

While De Grasse couldn’t beat Bolt Wednesday night, he hopes that forcing the 29-year-old Jamaican to run hard will make him at least a little more vulnerable for Thursday’s final. Bolt hasn’t lost a race at a major championship in eight years, aside from the 100 meters at the 2011 world championships when he was disqualified for a false start.

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“He’s a great competitor,” De Grasse said. “I just wanted to go out there and try to challenge him, push him to his limits a little bit. I didn’t want to give him the easy run. I wanted to make him work a little bit to get into the finals.”

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