Both overall Crystal Globes had already been sealed by Norway's Tiril Udnes Weng and Klæbo going into the final races on a tough five kilometres course which included 772 metres of climbs in the Finnish resort.

Kalvå made it a day to remember with a first triumph on the World Cup circuit at the age of 30, prevailing in a star-studded six-way sprint.

She made her move descending into the Lahti Stadium, and crossed the finish line in 51min 4.3sec.

"It was amazing," Kalvå said.

"I felt so good today and I had amazing skis so I just had to believe in the process and give it all in the finish.

"It was amazing to finish first.

"It was a hard race - it was the last race of the season and everyone is tired so it goes a little bit up and down, but I felt good."

Jonna Sundling of Sweden finished second for the fourth consecutive World Cup race in 51:05.2, with Germany's Katharina Hennig rounding off the podium in 51:05.4.

The 15km skiathlon and 30km mass start classical world champion Ebba Andersson of Sweden placed fourth at 1.3 off the pace, while Finland's home favourite Kerttu Niskanen placed fifth 3.3 slower than Kalvå.

Niskanen led the World Cup distance standings by 22 points going into the race, and secured the points required to top the rankings through the 7.5km and 12.5km checkpoints.

She finished on 1,180 points to the 1,086 of the United States' Jessie Diggins, who could only finish 22^nd in Lahti with a time of 52:19.5.

The season's overall winner Weng placed 18^th in 52:12.0.

In the men's 20km classic mass start, Klæbo finished the season with six consecutive victories, and equalled the record of 20 wins in a season set by his compatriot Therese Johaug.

Finland's Iivo Niskanen led for most of the second half of the race, but Klæbo stayed with him and launched an attack on the final climb which pulled him clear of his rivals.

He triumphed in 44:13.0, beating the second-placed Pål Golberg, also of Norway, by 5.4.

William Poromaa of Sweden completed the podium in 44:19.0, beating Mikael Gunnulfsen of Norway in fourth by 0.7.

Niskanen fell away and had to settle for ninth in 44:21.6.

Klæbo was thrilled with how he ended a stunning season.

"It’s the perfect way to finish off the season," he said.

"All the way I was hoping people would push a little bit harder so we could come faster to the finish line and start celebrating.

"It feels amazing to equal the record of 20 wins - nothing I have ever dreamed of before the season started with injury and everything - so I’m just so satisfied and really proud.

"For sure, it’s my best season ever."

Golberg made sure of the distance Crystal Globe by the first 7.5km checkpoint, and finished with 1,258 points for the season to Klæbo's 1,154.