Has Krueger gone too early? It's common for skiers with big leads to be wound in during the closing stages of these races. Downhill section, Musgrave tucking the skis under his arms.

Krueger's lead in increasing....

Here we go then, one circuit of the 3.75km course to go.

Simen Hegstad Krueger, the Norwegian that feel at the beginning of the race, leads. Andrew Musgrave, form Great Britain, is second.

Krueger has quite a lead, about nine seconds. Musgrave leads a big chasing pack.

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Musgrave, wearing number 10, pumps his arms and sways side to side, ploughing through the snow in the air temperature of around -16 degrees. Business end time as the floodlights peer through the gloom.

To put into context how remarkable a Musgrave medal would be, the best performance by a Briton in cross-country skiing was Musgave's 29th place in the sprint in Sochi four years ago. Great Britain have never (ever) won an Olympic medal in a skiing event.

He's second!

Scott Richardson: Come on Andrew Musgrave, big push towards the end! Unbelievable stamina and so much excitement on an early Sunday morning.

Dario Cologna, the defending champion, once again eases himself into the top two, behind Norway's Hans Christer Holund. Andrew Musgrave remains in the top six. He lives in Norway, studying in Trondheim, so he is learning from the best. There's still more than a fifth of this race to go, but he's in with a shout of an unlikely and historic medal.

Rob Walker
Commentator on BBC TV

It's a very big group at the front. The longer they leave it, the more intense this becomes.

This is beginning to get quite exciting, Andrew Musgrave is right in the mix with the very best.

Not surprisingly, Musgrave rates his event as the toughest in the Games.

To be honest, I can't think there's anything fun about skiing for 30km, a lot of it uphill.

Here's what he has to say about it...

Caroline Chapman
BBC Sport in Pyeongchang

I’ve found Team Musgrave! Posy, his sister, is joined by her parents and boyfriend. They are watching intently and are really happy with brother Andrew’s progress so far.

Image source, BBC Sport

Dario Cologna is making a move back up the field. He's picked off Andrew Musgrave, but the leading pack are so close together that it's hard to pin a skier to a particular position for too long. Musgrave, wide blue shades and blue headband, dips his head and puffs out his cheeks into another big climb. We're into the final 10km.

If you're wondering what's going on, watch our handy 30-second guide to find out how it works.

Lucy Jones: Come on Andrew Musgrave! You are making my insomnia fantastic!

Maggie: Oh god, I've been watching this skiathlon for 10 minutes and I'm exhausted. These guys must have the lung capacity of a whale. The strength to get up those hills...

Scratch that, Musgrave has gone fifth. Norwegian Simon Hegstad Krueger has got himself into, despite falling at the start. Dario Cologna has gone backwards. The leading pack is of about 15 skiers, all toiling up a brutal slope. You can tell that they are really starting to feel the burn.

Rob Walker
Commentator on BBC TV

This is absolutely superb from Andrew Musgrave, it really is.

He's an absolute trailblazer for the sport in the UK and, maybe, this will spark a cross-country skiing interest in any young boys or girls that are up early to see this.

He has some of the very best cross-country skiers in the world behind him at the moment.

The lead is changing hands fairly regularly, but the presence of defending champion Dario Cologna in the top two or three remains constant. Unsurprisingly, the skiers are moving with a little more freedom now they have switched to the free style. Musgrave may have slipped a couple of places...

Ollie Williams
Commentator on BBC TV

Andrew admitted he might have got carried away in Sochi, but he is the one driving much of his own hype this time around by saying 'look, I've learned my lessons'.

He knows that if he continues the way he's been going, he has it in himself to medal - maybe in the 15km - or maybe here.

Andrew Musgrave finished 29th in the sprint in Sochi. At the moment, he's seventh, only 2.5 seconds off the lead. He's in with a shout of what would be a remarkable medal. You could throw a blanket over about 15 of the skiers at the front, mind.

Image source, EPA

Dutchman Sven Kramer is bidding for a three-in-a-row in the 5,000m but he may not have things all his own way when the action starts at the Gangneung Oval shortly.

The 31-year-old suffered his first defeat over the distance for 26 months when he lost to Bob de Vries at the Dutch trials and he also has competition from former team-mate Ted-Jan Bloemen.

Bloemen switched nationalities to Canada in 2015 and broke Kramer's world record in December.

Image source, Reuters