Norway's Karsten Warholm scored a surprise victory in the men's 400 meters hurdles at the World Athletics Championships here.

The 21-year-old shocked the field with a time of 48.35 seconds for the gold on Wednesday night. Turkey's Yasmani Copello took silver in 48.49 and former twice world champion A Kerron Clement of the United States won bronze in 48.52, reports Xinhua news agency.

"I truly don't believe it. I've worked so hard for this but I don't know what I have done. This is an amazing feeling."

"I'm world champion, that's crazy. A lot of hard work and dedication has got me here so thank you to my coach for getting me in a position to challenge for a world title," Warholm said.

"I got out well and managed to hold it really well. I'm so proud of my performance. I hope people back in Norway are as happy as I am."

Warholm, a former European junior decathlon silver medallist two years ago, has found that 400m hurdles is his event since this season, winning two Diamond League titles in Oslo and Stockholm.

"Decathlon gave me a really good base coming into the hurdles," he said. "All the credit goes to my coach for making me a world class hurdler," he said.

Copello, the European champion and 2016 Rio Olympics bronze winner, was satisfied with a silver. 

"To win a world championship medal is my dream. My coach just told me to relax and now I have a medal, I'm so happy. It's been an incredible experience," he said.

Clement, who won the world champion in 2007 and 2009 and the Olympic gold last year, said a mistake at the last moment cost him the gold medal.

"My legs just weren't there off the last hurdle and that cost me the gold. You can see I came off it pretty badly. On another day I would have won but I'm happy to add another medal," the 31-year-old said.