The first day of medals action at the World Championships in the Finnish city also saw Federico Pellegrino of Italy storm to victory in the men's sprint event.

Falla secured her maiden individual title after she crossed the line in a time of 3min 02.34 sec, finishing in front of American duo Jessica Diggins and Kikkan Randall.

Diggins, team sprint world champion in 2013, was 1.66 seconds slower than the Norwegian, with Randall 3.76 seconds back.

Two of the pre-race favourites - Stina Nilsson of Sweden and Natalia Matveeva of Russia - were involved in a crash during their semi-final.

It ruled Nilsson out of medal contention as she was given a yellow card and therefore finished last.

"I was really nervous before today’s race," said Falla. 

"I am really satisfied with the way I skied today.

"In my quarter-final I used a lot of power to pass the other girls. 

"In the semi-final and final I was in the front almost all the time, which is my favourite tactic."

Pellegrino, the reigning FIS Cross-Country World Cup sprint champion, demonstrated his considerable pace as he was second going into the final curve before he surged to the line to claim an impressive triumph.

The Italian completed the course in 3:13.76, just 0.15 seconds faster than eventual silver medallist Sergey Ustiugov, to clinch his first-ever World Championships gold medal.

Johannes Hoesflot Klaebo of Norway came through to take bronze.

"I came to Lahti really relaxed," Pellegrino said. 

"I knew if everybody on the team including me do the best I can win. 

"I had great skis and really good legs and that is was why I won."

The Nordic Ski World Championships continue tomorrow with action in Nordic combined and ski jumping.