USA's Jennifer Valente then gets a few points and is pushing to join the back of the group.

Valentine Fortin of France picks up the early points and then bags another 20 for catching the last rider.

Like the scratch race, the tempo is also contested over 30 laps totalling 7.5km.

From the end of the fifth la, one point is awarded to the first rider each lap and if one rider gains a lap on their rivals, they score an extra 20 points.

Back to the omnium now, and Great Britain's Katie Archibald should be satisfied with fourth place and 34 points from the opening event.

However, heading into the tempo race, the Scot will be wary of Belgium's Lotte Kopecky, who crossed in sixth.

Image source, PA Media

Dutch rider Jeffrey Hoogland takes the win in heat three while Thomas Cornish joins the Australian contingent in the semi-finals and Malaysia's Azizulhasni Awang is also among those to go through.

Matthew Glaetzer and Great Britain's Hamish Turnbull lead out and although defending champion Harrie Lavreysen and Kevin Quintero get in front, Glaetzer and Turnbull also qualify.

The motorised 'derny' sets the pace then peels away to leave the riders to battle it out and Jack Carlin leads into the sprint.

Australia's Matthew Richardson storms back to nick the win but no matter, the first four go through to the semi-finals.

Image source, Reuters

Jack Carlin and Hamish Turnbull have the chance to win a medal in the men's keirin tonight, beginning with the quarter-finals.

Carlin, 26, is competing on home turf and has already claimed a bronze in the men's sprint in Glasgow.

He goes in heat one while team-mate Turnbull, 24, goes in heat two.

• Men's keirin quarter-finals (18:01)
• Women's omnium - tempo race (18:19)
• Women's sprint finals (18:33)
• Men's keirin semi-finals (18:41)

• Women's omnium - elimination race (18:58)

• Men's points race (19:15)
• Men's keirin finals (20:11)
• Women's omnium - points race (20:21)

There's not much in it heading into the final lap and New Zealand's Ellesse Andrews gives it everything she's got but Germany's Lea Friedrich stays clear to make it two from two and book her spot alongside Great Britain's Emma Finucane in the final.

Back to the women's sprint semi-finals, and now it's Emma Finucane who is looking over her shoulder.

Emma Hinze picks up the pace just before the bell but Finucane stays clear during the final lap, with the German not even able to reach Finucane's back wheel.

The Welsh rider will have a shot at gold later.

Image source, Reuters

New Zealand's Ally Wollaston is well clear to take the maximum 40 points, with Katie Archibald fourth heading into the final lap.

And it stays like that with USA's Jennifer Valente staying second (38 points) and Italy's Letizia Paternoster third (36).

Ally Wollaston has gone solo and is well clear of Aline Seitz with five laps to go, and Katie Archibald at the front of the peloton.

With 10 laps to go, Ally Wollaston and Aline Seitz have gone clear.

Katie Archibald mounts the first attack with just over 20 laps remaining, much to the delight of the Glasgow crowd.

Katie Archibald is back mixing it with the world's best in Glasgow after a frankly awful 2022.

The 29-year-old Scot had planned to have shoulder surgery in January but then suffered a fractured back in March and contracted Covid-19. In April, she broke her collarbone and suffered a concussion in a crash during the omnium points race at a Nations Cup event in Glasgow.

Then at the end of May she suffered ligament damage in both ankles when she was struck by a car while on a training ride, which forced her out of the Commonwealth Games in Birmingham.

But far worse was to follow in August as just two days after winning the Scottish mountain bike cross-country championship, Archibald's partner Rab Wardell died while he slept beside her.

Archibald has talked about how she tried to save Wardell, who was aged 37, after he suffered a fatal cardiac arrest during the night.

The omnium is a multiple race event which features four races - scratch, tempo, elimination and points - and the winner is the rider who finishes with the most points.

It begins with the scratch race, where all riders start together and the first over the line picks up the most points.

The women's event is contested over 30 laps totalling 7.5km - and it's now under way.

Richard Winton
BBC Sport Scotland

Being in the midst of a race is Olympic champion Katie Archibald's "happiest place in the world".

In those moments, nothing else matters. The nerves vanish. The emotional crash has yet to come. It's just her, a bike, and her competitors.

That feeling of being free will be heightened at the World Championships in Glasgow over the next week or so.

In her home city. At the Chris Hoy Velodrome, the place she first walked into as an 18-year-old with pink hair and a lip ring. The place where the dream began.

But dreams don't always come true. Last year was a horrendous one for the 29-year-old.

Saturday night proved the culmination of an inspiring journey back to the top of cycling for Katie Archibald.

She had a woeful year with injuries in 2022 and suffered the tragic loss of her partner at just 37, but she found the strength to continue to race.

Along with Anna Morris, Josie Knight and Elinor Barker, she rode superbly to help Great Britain win a first gold in the women's team pursuit since 2014. It was a victory that Archibald said "validated" the team's feeling that they are the best in the world.

Tonight she has the chance to add an individual medal and a third world omnium title, in front of what is sure to be a raucous home crowd at the Sir Chris Hoy Velodrome.

New Zealand's Ellesse Andrews leads out in the first race of her semi-final with Lea Friedrich but the German dives underneath to ease home.