Joyciline Jepkosgei is among the leaders in the women's race, having ran a personal best to take the win in London last year.

That time of 2:17:43 puts the former 10km world record holder 20 seconds behind Yalemzerf Yehualaw, and she'll be hoping her experience from last year can help her bridge that gap.

One other athlete in the field has previously run under 2:18:00 and that's Ethiopian Ashete Bekere, who crossed the line third last year/

Bekere posted her best time, 2:17:58, at the Tokyo marathon in March.

Image source, Getty Images

Louise Barth: Good Luck to all our St John's Ambulance marathon runners today, you are amazing. Good Luck also to our fabulous First Aid Volunteers all across the route there to help every runner when they need it

Rob Kerr: Best Wishes to everyone that is taking part in London Marathon today. You raise so much money for your chosen charities, us lazy sofa-surfers salute your amazing endeavours warmly and with much respect to you all.

The elite women have slowed slightly, passing 15km in 48 minutes 51 seconds.

Ethiopia's Yalemzerf Yehualaw still looks relaxed as she sticks right behind the sole remaining pace maker at the front, with seven other athletes for company.

Paula Radcliffe
Women's marathon world record holder on BBC TV

Big step up for British runner Andy Butchart pacing the marathon, I think it is in his plans to move up to running it himself in the future. Experiencing this today will inspire him on to that.

He was asked to pace for Mo Farah originally and it's a swift pace they've asked for.

Ethiopian Sisay Lemma is the reigning champion and returns to defend his title today.

But he has tough competition.

Compatriot Kenenisa Bekele, considered one of the greatest distance runners of all time, is among the athletes looking to deny him.

Image source, Getty Images

Paula Radcliffe
Women's marathon world record holder on BBC TV

Such a beautiful sight, all of those runners and colours of outfits. They will learn a lot about themselves throughout this 26.2 miles - they will change a bit. I'm looking forward to seeing all those emotions on the finish line.

One brave chap sprints off the front to try and put the elite athletes under early pressure.

They don't seem too concerned, however. Hopefully he doesn't regret that effort too badly later on...

What a sight!

The elite men's field leads out a sea of runners as more than 40,000 people prepare to begin their marathon journey.

Good luck to every single one of them!

The national anthem is played as we near the start of the elite men's race and, behind them, the mass start.

The Lionesses return to their podium ready to sound the horn for the third and final time his morning.

Deep breath. It's almost time!

In the elite wheelchair races, defending champion Marcel Hug still leads the men's event but, still, to his frustration, the USA's Daniel Romanchuk remains right behind him. In the women's, it's still Catherine Debrunner out in front.

Do keep your messages of support coming in! We're loving hearing about who you're cheering on, and why, during today's London Marathon.

I'm sure a fair few taking on the marathon today will have struggled for sleep last night. The pre-race nerves are very real.

Hopefully everyone's alarm clocks have come through for them. The mass start - along with the elite men's race - is less than 10 minutes away!

BBC One

TV coverage is just about to switch over from BBC Two to BBC One, where it will stay until 14:35 BST.

A reminder that you also have the following options on BBC iPlayer, BBC Sport website and BBC Sport mobile app:

08:30-17:00 - elite races and finish line

08:30-14:35 - uninterrupted race coverage

Then, later, the highlights will be on BBC Two from 17:20-18:20.

At 23 years old, Yalemzerf Yehualaw could be setting records for some time to come.

The Ethiopian set a world record over 10km in February this year.

She then recorded the fastest ever time by a female debutant over the marathon distance, clocking 2:17:23 in Hamburg in April.

So, its been a pretty good year so far. Could there be another big statement performance to come today? In Brigid Kosgei's absence, she's the fastest in the field and is sat immediately behind the pacers after 25 minutes of running.

Image source, Getty Images

It's been a fast start to the elite women's race.

They've covered the first 5km in 16 minutes and one second - so they're currently on course for around two hours and 15 minutes. Rapid.

So, with no Brigid Kosgei in the elite women's race, who is going to be pushing the pace at the front?

The women's field still features several world-class athletes, including Kosgei's compatriot and last year's London Marathon winner Joyciline Jepkosgei.

Meanwhile, Ethiopia's challenge could come from Yalemzerf Yehualaw.

The 23-year-old set the fastest debut time for a marathon earlier this year and holds the world record over 10km.

It's currently nice and dry in London. But will that last?

The forecast in previous days suggested there was a chance of some rain. Hopefully it stays away...