Great Britain's Matt Walls still leads overall from Benjamin Thomas and Jan-Willem van Schip, who tries to counter - 54 laps remain with plenty of points on offer.

Chris Boardman
Olympic cycling champion on BBC TV

Walls is now playing a canny game and not over-extending himself chasing shadows.

Everybody will be expecting him to break again.

Elia Viviani is the next rider to try and make a move. All the riders are desperately doing the maths while scrambling for points. It's like asking a long-distance runner to do Sudoku.

Benjamin Thomas, who sat third heading into this one, nips to the front in a bid for points.

The Frenchman narrows the deficit slightly but Matt Walls still looking good.

A quarter of a way there. Matt Walls is 75 laps from an Olympic gold medal. Actually, when you put it like that it sounds like quite a lot. Brutal, this omnium. But so far, so good for the Team GB rider.

Image source, Getty Images

Sir Chris Hoy
Six-time Olympic cycling champion on BBC TV

In the midst of it you will be looking at the points on the scoreboard and our coaches with one word commands and gestures. You have to have a computer for a brain... and a motorbike in your legs!

Or are they?!

An immediate reply from Australia as Caitlin Foord nods home to make it 4-2.

Just over ten minutes gone in this second-half - are we going to see an upset?

Chris Boardman
Olympic cycling champion on BBC TV

Walls on the front here trying to force a split in the group. There you go, daylight - he swung up the track as if he was giving it up and straight back down ahead.

Quite high risk though - he's gone quite early and the pace behind has lifted.

Matt Walls makes a break, soaring away from the field. The British rider should bag a few points here, he's gunning for gold. Punchy stuff and he claims a lap! A total of 25 points right there.

It's 20 points for gaining a lap and another five for being ahead for each sprint.

So plenty to play for...

It's another one in the bag for Carli Lloyd and you have to think that is it for the USA - they're looking comfortable here.

Disappointing for the Matildas who perhaps don't deserve this scoreline - but you just can't give Lloyd that much space and she is clear through on goal to put the USA out of sight.

BBC Sport

Jack Carlin spoke to BBC Sport after making the semi-final: "Another day in the bag see what happens tomorrow, bike's feeling good. Legs are feeling alright but everyone's sore at this point in the week.

"I think we take each race as it comes, keep calm and what will be will be.

"Jason was struggling today - fatigued kicked in from the team sprint but he still went out and gave it his all and that's what Olympic champions do."

And here we go. Hope you've got a brew and a biscuit ready.

If you're not an omnium addict after this morning's action, then why not?!

Great Britain's Matt Walls leads the way heading into the final of four races, with this one the 25km, 100-lap points race...

Jack Carlin is looking very strong. His day is done. On to the semi-finals of the men's individual sprint tomorrow for the British rider.

We're back underway at the Kashimo Stadium for the second-half of this thrilling encounter between the World Champions and the underdogs.

It's been fairly even possession wise but the USA have dominated the shot counter with 13 to Australia's seven.

The Matildas have built themselves a fair old mountain to climb if they're hoping to come away with some hardware.

Jay Briers: Gutted for Kenny. Can’t help but wonder if it was one year too far. He looks tired. Time to pass the torch to Carlin.