Hundred-meter world record holder Usain Bolt entered a news conference today only 80 percent sure he’d take a stab at a “double” in the 100 and 200-meter dashes. He emerged 100 percent sure.

Bolt’s prospects of a “double” in the two events, last accomplished by Carl Lewis in Los Angeles in 1984, has become one of the hot storylines of the Beijing Games. The 21-year-old Jamaican was already the favorite for gold in the 200 meters, his forte. He darted into the thick of 100-meter contention with sprints of 9.76 and 9.72 in May, the latter time nipping compatriot Asafa Powell’s previous mark of 9.74.

The Bolt camp had said all along that his coach Glenn Mills would decide whether or not he’d go for the “double”, which has the downside of added training and racing and potentially harming his chances in the 200. On Sunday, the AP confirmed through Bolt’s agent that he would compete in both events.

But apparently no one told Bolt that. At the start of a Q&A with media in Beijing on Tuesday organized by Jamaican team sponsors Puma, Bolt said he was 80 percent sure he’d run in both races. “Actually my coach hasn’t really told me exactly, but I’m just guessing eighty.” Then a reporter informed Bolt of Sunday’s reports, to which he responded: “This is first time I’m hearing that, actually.” Bolt recovered swiftly and good-naturedly. He said he’d never had any such miscommunication before with Mills, whom he praised as a “father figure”. By the end of the news conference was switching gears with a grin. “I thought I was 80 percent sure I was going to double, but now I’m 100 percent sure I’m going to double.”

Nor did Beijing’s infamous smog and oppressive August humidity appear to factor in the decision. Bolt said he’s been training in a camp far outside the capital (in Tianjin, he thought) so hadn’t had a chance to assess the ill-reputed air himself. But he showed no concerns about the conditions compounding the physical challenge of the “double”. He had prepared for it by running the 100 and 200 meters at meets over the course of this season, and had learned to run easy in trial heats, he noted. “So we’ve conditioned myself pretty much for this, so I’m kind of used to the heat, so I don’t think it’s going to take too much out of me.”