NEW YORK - After winning his sixth gold medal of the Beijing Olympics, Michael Phelps feared he wouldn't be strong enough to win his seventh.
But a mistake by rival Milorad Cavic allowed Phelps to pull out an improbable victory in the 100-meter butterfly.
Phelps, who went on to break Mark Spitz's record by winning eight golds in China, discussed his performance in an interview with the CBS news show "60 Minutes," to be broadcast tonight.
After winning the 200 individual medley, Phelps expressed his fears to coach Bob Bowman.
"I got nothing left," he remembered saying to Bowman, according to an excerpt of the interview released by the network.
Bowman saw it, too.
"If you look at the pictures right after the [200 IM] and even when I was standing there and he was in the water, I thought, 'Wow, he is really tired right now,'" Bowman told "60 Minutes."
In the fly, Cavic was clearly ahead as the two swimmers approached the wall. The Serbian glided to the finish with his arms outstretched, while Phelps took an extra half-stroke that gave him the victory by one-hundredth of a second -- the smallest possible margin.