THOUSANDS of runners in are waiting with baited breath for the firing gun to blast off on of the world’s greatest mass running events.

The final countdown is underway for the launch of Hampshire’s Morrisons Great South Run on Sunday.

This weekend landmark race celebrates 25 years since the race moved to Portsmouth after the debut run was launched in Southampton.

Tens of thousands of people will take to the streets to watch 25,000 runners tackle an epic 10 mile route though the city.

The famously ‘flat and fast’ course route starts and climaxes at Clarence Esplanade, Southsea, taking in some of the city’s most iconic landmarks including the Spinnaker Tower, Southsea Common and Portsmouth Historic Dockyard past HMS Victory, HMS Warrior and the Mary Rose Museum.

Double Olympic champion sailor Ian Percy OBE will sound a starting klaxon and to the tarmac himself to run in memory of late sailing partner and friend Andrew ‘Bart’ Simpson who tragically died in an America’s Cup training accident in San Francisco Bay in May 2013.

Mr Percy will be raising funds for the Andrew Simpson Sailing Foundation enabling young people to take up the sport.

Runners will be kept motivated by charity cheering points and boost zones run by local charities and organisations who are among those benefitting from runners raising tens of thousands of pounds for good causes.

It is the culmination of three sister events taking place over the weekend launched with a 5KM run on Saturday, October 24.

The shorter race features a women-only starting wave, staged in partnership with This Girl Can: Running, an advertising campaign urging women to embrace a healthier lifestyle.

The initiative’s founder Sam Mollaghan, from Bournemouth, will be the wave’s honourary starter before running the course herself.

Hot on their heels is the Morrisons Junior and Mini Great South Run - the biggest children’s running event in the South.

This year it will be powered by magic with Disney-themed fancy dress 1.5KM and 2.5KM courses for children aged three-15 and a special character setting them on their way.

David Hart, Great Run Company communications director, said: “The Morrisons Great South Run weekend offers something for all ages.

“Thousands of charity fundraisers, fun runners and families travel to Portsmouth from across the UK to experience this world class event.

“This year we’re celebrating 25 years in Portsmouth so it’s sure to be a weekend to remember, but even if you’re not running come down and show your support.”

Other famous faces taking part this year include the comedian Hugh Dennis, while European 10,000m champion Jo Pavey will compete in the women’s elite field.

Southampton North and Romsey MP Caroline Nokes is also running the main course in aid of eating disorders charity Beat.

Don't miss your eight-page souvenir picture special in Monday's Daily Echo.