SYDNEY (AFP) - Australian Eamon Sullivan has revealed he snubbed his coach's instructions in going all out to recapture the 50-metre freestyle world record from French rival Alain Bernard at the Australian Olympic trials.

Sullivan beat Bernard's record by nine-hundredths of a second in a time of 21.41 seconds in Thursday's semi-final and said he could go even faster in Friday's final.

Bernard held the record for just four days, with his 21.50 at the European championships bettering Sullivan's previous mark of 21.56, set in Sydney in February.

Sullivan was frustrated to have failed to beat Bernard's 100m freestyle record in winning Wednesday's final and decided to go against the technical instructions of coach Grant Stoelwinder in the 50m scamper.

"The last 25m was all brute force and no technique, I was just slugging away," Sullivan told reporters after the race.

"I threw the coach's instruction out the window and started slugging away.

"I thought it was good to get in there and get that frustration out and it worked.

"I think if I can find a right combination between what I want to do and doing what the coach thinks is best, then it is going to work out.

"But I just wanted it that badly, I just thought 'oh, stuff him': I will put my head down and bum up and just throw my arms around."

The rapidly improving 22-year-old sprinter said his rivals -- including American Olympic champion Gary Hall Jnr, who had made disparaging remarks about Sullivan -- would now have to give him some credit.

"Yeah, I think they will be taking me a bit more seriously now. I don't really care which way they take me.

"I know what I'm capable of and that I can perform under pressure, so however people think of me... is not really going to affect how I'm swimming and my mental preparation."