After claiming three silver medals and one bronze at Pyeongchang 2018, Bolshunov finally tasted success as he stormed to victory at the National Cross-Country Skiing Centre in Zhangjiakou.

Iivo Niskanen of Finland led at the halfway point before Bolshunov picked himself up from an early fall to pull away from the rest of the field.

Bolshunov waved the ROC flag as he crossed the finish line in 1 hour 16min 9.8sec - more than a minute quicker than compatriot Denis Spitsov in second place, while Niskanen was two minutes further back in third.

Russian athletes are competing under the ROC banner as part of sanctions imposed by the World Anti-Doping Agency against Russia in connection with the manipulation of data from the Moscow Laboratory.

Bolshunov was irked when asked to explain his emphatic display, insisting there are clean athletes competing for the ROC.

"You're hinting at doping… this should have nothing to do with sports," said Bolshunov.

"We have clean sportsmen, clean athletes who are at the Olympics who do doping tests almost every day.

"We have to fill out these forms indicating where we will be training, what time, we show the time window when we can take a test, when we are going to be travelling, if I use a plane or a train from one place to another.

"I believe it's wrong to ask us these questions - you don't achieve these results all of a sudden, you don't become an Olympic champion, because it takes years and years of training."

Bolshunov also invited journalists to attend training sessions to showcase how hard the ROC cross-country skiing team work.

"After you have seen how we train, I believe you and your audience will never have these questions again," said Bolshunov.

Two-time Olympic gold medallist Simen Hegstad Krüger of Norway was ruled out of the event after testing positive for COVID-19.

It was one of several cases in the Norwegian cross-country skiing team camp as they were forced to arrive in Beijing later than planned.

Krüger headed a Norwegian one-two-three in the men’s skiathlon at Pyeongchang 2018 but they failed to earn a medal this time around.

Norwegians Hans Christer Holund and Pål Golberg came fourth and fifth, respectively.

While Bolshunov stormed clear, Spitsov slipped in the final few kilometres before finishing in a time of 1:17:20.8, while Niskanen bagged bronze in 1:18:10.

Cross-country competition is due to resume on Tuesday (February 8) with men’s and women’s sprint free events.