With only two assured qualification spots from his heat, the 100 champion switched into a higher gear at the end of his race when, unexpectedly, Anaso Jobodwana appeared on his left shoulder.
Bolt momentarily gritted his teeth but soon turned them into a grin as he held off the South African and took first place in his semifinal heat in 20.12 seconds. He never showed any unease about his right foot.
Curtis Mitchell was top qualifier in 19.97, but saw all his American teammates eliminated from the final. Isiah Young missed it by .03 seconds.
Bolt was joined in the final by Jamaican teammates Nickel Ashmeade and Warren Weir.
Bolt had been troubled by a sore foot since he regained his 100 title on Sunday.
“I worked on it over the four days, got a lot of work done,” Bolt said. “Right now, I’m good.”
If Bolt wins, he goes into the 4×100 relay seeking to win three golds at the worlds for the second time, matching his feat at the last two Olympics.
Another Jamaican will try to get one step ahead of Bolt. Shelly-Ann Fraser-Pryce already has the 100 title and will now go against Olympic champion Allyson Felix of the United States in the final of the 200.
Felix is also seeking three golds. If she wins the 200 and adds the 4×100 and 4×400 relays, it would equal the three golds she won at the London Olympics.
And after three silver medals on Thursday, the United States is ready to get in that golden mood again, and with the men’s long jump, 4×400 relay and shot put scheduled, the opportunity is certainly there.
At the longer distances, Mo Farah is looking for a double. The 10,000 champion is favored again to defend his title in the 5,000. He got a similar 5,000-10,000 double at last year’s London Games.
Friday’s other final is the women’s hammer throw.
In the 100 hurdles, Olympic and defending champion Sally Pearson shook of the injury worries that slowed her this season and set a season’s best time of 12.62 seconds in her heat, still .07 seconds behind leading qualifier Brianna Rollins of the United States.
Dawn Harper, the 2008 Olympic champion from the United States, finished only third in her heat but still advanced.
Off the track, pole vault great Yelena Isinbayeva backed off from her comments criticizing homosexuality. The Russian said she “may have been misunderstood” when she condemned homosexuality and criticized Swedish high jumper Emma Green Tregaro for painting her fingernails in the rainbow colors to express support for gays and lesbians.
“English is not my first language,” Isinbayeva said. “Let me state in the strongest terms that I am opposed to any discrimination against gay people.”