With pre-Games medal favourite Jake Wightman out with a hamstring injury, it looked like Team GB would be without a representative in the men’s 800m final after Ben Pattison and Elliot Giles failed to qualify.
However, Burgin, going in the last semi-final, pulled off a personal best of one minute 43.50 seconds to finish third and go through as one of the two next fastest.
“I don’t really know what to say. It sort of came out of nowhere,” said 22-year-old Burgin. “I wouldn’t have believed it a month ago, I wouldn’t have believed it a few weeks ago.”
In the women’s 4x400m relay, Team GB’s Laviai Nielson battled down the home straight to cross the line in second in three minutes 24.72 seconds to qualify for Saturday’s final.
Meanwhile, in the men’s event, Charles Dobson held off a late charge by the United States’ Chris Bailey, who had a strong anchor leg to finish third after 16-year-old Quincy Wilson struggled in the opening lap.
There was disappointment for GB’s Cindy Sember, who crashed on to the track floor in her women’s 100m hurdles semi-final after clipping a barrier with her trailing leg.