Shaunae Miller (BAH) of Bahamas dives over the finish line to win gold in the women's 400m final during the 2016 Rio Olympics in Brazil, Aug 15, 2016. [Photo/Agencies]

RIO DE JANEIRO - Bahamian Shaunae Miller launched herself over the finishing line with a desperate dive to pip American Allyson Felix to Olympic 400 metres gold by the slimmest of margins in a thrilling final on Monday.

After literally flying across the line in a personal best time of 49.44 seconds, the 22-year-old lay on the track, shaken up and exhausted, as she waited for the scoreboard to confirm she had clinched her first major title.

"I didn't see anyone until the last 20 metres and the only thing I was thinking was that I must get that gold medal," said Miller.

"I think (the dive) was just a reaction, my mind went blank, the next thing I knew I was lying on the ground. I've got a few cuts and bruises but I'm okay.

"This is the moment I have been waiting for. I am just so happy, so grateful, such emotions I just can't say."