The double amputee Olympic hopeful was more than three seconds off his season best and nearly three seconds off the qualifying time for the London Games after facing a strong headwind in the home straight at the NMMU Stadium in Port Elizabeth.
Pistorius ran in lane eight and held back over the last 50 meters to finish second to provincial team mate Ranti Dekgate, qualifying for the semifinals at the two-day nationals in the south coast city.
"We thought we'd have the wind as an assistance into the home straight but it started working against us," Pistorius said. "I'm feeling confident, I think it's going to be a good workout." Former world champion Caster Semenya went straight into Saturday's 800 final at the university stadium after a string of withdrawals in her event meant it wasn't necessary to hold heats or semis on Friday. The 21-year-old Semenya was due to run her second two-lap race of the Olympic year.
It leaves the 2009 world title winner and last year's world silver medalist with just one race at the South African nationals to hit her second qualifying time for London, making herself eligible for the Olympics and easing the pressure after a sluggish start to the season under new coach Maria Mutola.
Her time at last year's worlds in Daegu, South Korea, counts for Olympic qualifying.
Having last month registered 2:03.60 in her only 800 race so far this year, Semenya needs to run another 1:59.90 time to qualify for her first Olympics. She still has at least two more meets in South Africa after the nationals and a number of European events to ensure she's eligible for selection.
Pistorius began his season with a morale-boosting 45.20-second run in Pretoria, giving him his first qualifying time of the season and leaving him needing one more run of 45.30 or better in an international meet to likely make history as the first amputee athlete to run at the Olympics.
"I'm flirting a little bit with the idea," Pistorius said trackside when asked if he was thinking about London yet. "The team still has to get selected. My job is just to work hard until then and prove I'm in the right condition to be quite a strong 400 meter athlete if I get called up."
Athletics South Africa ruled that athletes who want to go to the London Games must appear at the South African championships, attracting Pistorius, Semenya, Olympic silver-medallist long jumper Khotso Mokoena and former men's 800 world champion Mbulaeni Mulaudzi to the meet.
World bronze medal winner L.J. van Zyl is also listed to run in the men's 400 meters hurdles at the nationals, fulfilling his requirements and qualifying him for the games. He has already registered two Olympic-qualifying times.
