LUCERNE, Switzerland -- Double-amputee sprinter Oscar Pistorius fell short of the 400-meter qualifying time he needed Wednesday to make the Olympics, though the personal best time he ran could still get him to Beijing in the relay.

The 21-year-old South African shrugged off a pre-race distraction of threatened legal action against the IAAF and finished third in his heat in 46.25 seconds.

Though still outside the Olympic individual qualifying standard of 45.55, it was 11 hundredths faster than his previous best.

"I am so excited and so happy. I really enjoyed tonight," Pistorius said. "It was always going to be a very difficult task to achieve the individual time but there is still the hope of the relay."

South Africa selectors will choose their team for the Aug. 8-24 Beijing Games by the weekend and can invite him to join the six-man roster for the 1,600-meter relay.

To do so would defy a public request from the IAAF because the body believes his prosthetic legs are a threat to his own and other athletes' safety.

"I think it is the IAAF's last desperate attempt to try to get me not to qualify," Pistorius said.

In May he won an appeal at the Court of Arbitration for Sport to overturn an IAAF ban which prevented him competing against able-bodied runners.

On Wednesday the New York legal firm of Dewey and Leboeuf, which steered that case, threatened a second legal action against the IAAF.

"We believe the IAAF is obligated to immediately advise the South African Federation and Olympic Committee that it has no objection to Mr. Pistorius competing in the 4x400m relay at the Beijing Games," it said in a statement.

It also demanded that the Monaco-based IAAF withdraw a further comment that it was concerned it did not have the resources to check on the legality of Pistorius' Cheetah blade limbs every time he appeared at a meet. The CAS ruling cleared him to run only when using the type of blade that was subjected to laboratory testing to prove it gave no competitive advantage.

"That kind of implies that I would cheat at events," Pistorius said. "It is very sad that they think that."

"It is not my problem any more. I have proved all I need to prove. My job is to be on the track and enjoy what I do.

"There is nothing more satisfying to me than running times like I did tonight."