Jamaican Asafa Powell powered through the puddles to win the 100m in 9.87.
As the rain lashed down, the last thing the 7,000-strong crowd expected was a sub-10 second time, but the former world record holder stormed to victory in stunning style.
Powell, who only managed 9.95 in Beijing as he came fifth in the Olympic final, needed an impressive run to help him move on.
He said: "The conditions weren't perfect, but I'm very happy. It would have been different in the Olympics if I had run like this. But the past is the past and this is the present."
As the rain lashed down, the last thing the 7,000-strong crowd expected was a sub-10 second time, but the former world record holder stormed to victory in stunning style.
Powell, who only managed 9.95 in Beijing as he came fifth in the Olympic final, needed an impressive run to help him move on.
He said: "The conditions weren't perfect, but I'm very happy. It would have been different in the Olympics if I had run like this. But the past is the past and this is the present."