LONDON >> It was only a morning 400-meter heat, but Oscar Pistorius took a big step in Olympic history Saturday, becoming the first double amputee runner to compete in the Olympics.

In front of another full 80,000-seat stadium for a qualifying session, the South African cut through a mild morning sunshine on his carbon blades to reach the semifinals with a second-place finish after a strong second half to his race.

His time of 45.44 seconds was important enough, but didn’t quite match the announcement at the start — “This is Blade Runner Oscar Pistorius” — that marked his entry into the Olympics.