Cuba's Denia Caballero landed a shock win in the women's discus competition on Tuesday, her first-round effort of 69.28 meters beating all her rivals, including defending champion Sandra Perkovic of Croatia.

Olympic champion Perkovic salvaged the silver medal with a late effort of 67.39, having gone into the final round facing the prospect of going home empty-handed after a mediocre series of throws that contained three fouls.

The bronze went to Germany's Nadine Mueller, with her best of 65.53 also coming in the first round.

Caballero is small by discus standards, at 175 cm, and she was dwarfed by her fellow medal winners as they lined up for the mandatory post-event photos at the IAAF World Championships.

It has been a breakthrough year for the Cuban who also passed the 70-meter barrier for the first time in June.

"The first throw was very important for me. I wanted to put Perkovic under pressure," Cabellero told reporters.

It was a plan that worked as the triple European champion fouled with her first, third and fifth-round throws.

Perkovic might have been eliminated altogether had her 65.35 second-round effort gone a meter to the right and out of the permitted sector.

"It's been an amazing day," said the 25-year-old Caballero whose previous best performance was eighth place at the 2013 world championships.

"I've been praying for this medal. I wanted any medal but gold is the best."