Both fields were competing in sprint events in a competition which doubles as a leg of the International Ski Federation World Cup series.

Van der Graaff had never won a World Cup leg before today and had only managed a solitary second place finish in Nove Mesto in 2014.

Roared on by home support, she skied superbly today to progress through the rounds and then comfortably win the final in 3min 25.80sec.

America's Sophie Caldwell finished in second place, 1.42 seconds behind, while Maiken Caspersen Falla of Norway placed third, 1.86 after the winner.

Ustiugov, yet to hear if he will be eligible to compete at next year's Winter Olympics in Pyeongchang following Russia's suspension by the International Olympic Committee, was a less surprising men's winner in 2:57.28.

Federico Pellegrini of Italy placed second in 2:59.54, while Lucas Chanavat of France finished third, a further 0.15 in arrears. 

The Tour de Ski consists of a series of stage races doubling as World Cup legs held across three European countries.

Action in Lenzerheide is due to continue tomorrow with a 15 kilometres classic race for men and 10km for women.

Pursuit races are then scheduled over the same two distances on Monday (January 1).

Further legs will then be held in the German resort of Oberstdorf on Wednesday and Thursday (January 3 and 4).

Action is then scheduled to conclude with two final races in Val di Fiemme in Italy next Saturday and Sunday (January 6 and 7).

Ustiugov is the defending men's overall winner.

Heidi Weng of Norway, who placed seventh today, was the female champion in 2016-2017.