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.