(CNN) -- Among the 35,000 runners lining up at this Sunday's London Marathon, there'll be the usual pre-race nerves, waves of excitement, and focus on the task ahead.
This year, there will also be silence.
Six days after Boston's Marathon was rocked by the bombing which killed three people and injured more than 180, the world will be turning its gaze to London's premier race.
It will be unlike any other race in its 32-year history, as thousands of competitors and spectators observe a 30-second silence ahead of the starting gun, in remembrance of Boston's casualties.
Haunting images of bloodied victims scrambling down smoldering streets, past upturned stands which just moments earlier had been filled with cheering family and friends, will no doubt loom large in the minds of Londoners this weekend.
Expect to see an ocean of black solidarity ribbons pinned to the chests of runners, as they wind their way past the Capital's most iconic landmarks such as Big Ben and Tower Bridge.
In another act of solidarity, for every competitor who crosses the finishing line, race organizers plan to donate $3 to The One Fund Boston, set up to raise money for victims of the blasts.
'In it together'
"Now there is a huge feeling of defiance," three-time London winner Paula Radcliffe told CNN.
"How dare someone attack sport and humanity in this way -- we are not going to be cowed," added the 39-year-old Radcliffe, who is the world marathon record holder.
That defiance is shared by the thousands of competitors who run the London Marathon to raise money for myriad charities.
"It's important to see on mass that we're in it together," said 36-year-old asset management worker, Ed Lucas, who will be running his first ever marathon on Sunday.
"It does make you reassess the race. But I think if anything, it will make people a lot more determined -- Brits are quite stubborn, they don't like being told what to do."
Another runner Matthew Huntington, 36, said his family -- including his two and five-year children -- would be coming to watch him.
"It never entered my mind to drop out and yes it made me even more determined to take part," added technical marketing manager Huntington. "If you're completely risk averse you would never leave the house."
Security will also be stepped-up at the event, which is the first international marathon to follow Boston.
There will be an increase in searches and officers on the street, London's Metropolitan Police Commissioner, Bernard Hogan-Howard, said.
"We've no reason to think people are any less safe than they were before the terrible events in Boston," he added.
Last year's Olympic Games has also bolstered London's credentials when it comes to hosting safe, international sporting events, Britain's culture secretary, Maria Miller, said.
"You will know from London 2012 last year, this country has a great deal of experience of ensuring our sporting events go well and that security is at the heart of the planning process. The London Marathon is no different," she told the Commons this week.
Deputy Prime Minister Nick Clegg promised security would be "double, triple, quadruple checked."
Show of support
With tight security measures in place, the public has been urged to get behind the great British sporting event -- as much for the competitors on the day as a sign of solidarity with Boston.
"Obviously, in light of what happened in Boston, we've had to have a look at security and we have a detailed and well-thought-out plan with the Metropolitan Police which we have year-in, year-out," London Marathon chief executive, Nigel Bitel, said.
"It's a great occasion, the London Marathon, and I know that people will want to come out and send a message of support to runners on the day."
Similarly, reigning marathon champion, Wilson Kipsang, told competitors to try and put security issues out of their minds as they wind their way along the 42 kilometer route from Blackheath to Buckingham Palace, home of the Queen.
"When you are running and you are thinking something like that can happen, you can't concentrate," the Kenyan told Athletics Weekly.
"We should have no fear during the race because security matters will be put in place and we will run feeling free."