Ahmed Hafnaoui, 18, from Tunisia stumped the field to win the gold medal in men’s 400m freestyle gold in the Olympic pool on Sunday in the 2020 Tokyo Olympics. He raced a sizzling final 50m to touch in 3:43.36 and overhaul Australian Jack McLoughlin(3:43.52) and US swimmer Kieran Smith (3:43.94), who took bronze.

It was a major breakthrough for the young gun, who has little pedigree on the world stage.

“I just can’t believe that, it’s amazing. I felt better in the water this morning than yesterday and that’s it. I’m the Olympic champion now,” he said.

“I just put my head in the water and that’s it. I just can’t believe it. It’s a dream come true.”

Elijah Winnington, who shocked Mack Horton at the Australian trials to deny his countryman the chance of defending his Olympic title, led through 100m.

But McLoughlin hauled him in by the 200m mark and looked destined for gold until Hafnaoui’s burst of electric speed as he zeroed in on the finish line.

-Japan’s Yui Ohashi wins gold-

Japan’s Yui Ohashi toppled defending champion Katinka Hosszu to win an Olympic gold medal in the women’s 400m individual medley.

The 25-year-old swam a scintillating breaststroke leg to take charge, touching in 4mins 32.08 secs ahead of US pair Emma Weyant (4:32.76) and Hali Flickinger (4:34.90).

“I swam believing in myself. I really did not think of winning the gold,” said Ohashi.

“A lot of people supported me so that I could exert all my strength. I really appreciate it. I had an enjoyable race. It is still like a dream.”

Hungary’s Hosszu, a dominant force since setting the world record at the Rio Olympics in 2016, was in touch over the first 200m but the world champion failed to deliver the killer punch she so often has before.

Flickinger set the early pace, turning first after the butterfly leg with Hosszu second, and the American maintained her lead through the backstroke.

But Ohashi pulled a body length clear in the breaststroke and no-one could rein her in, with the battle unfolding for the minor medals.