Farah's ultimate target, however, is some way removed from the rest of the field as, in his first crack at the revered 26.2 mile distance, he is planning to take on and beat one of the best elite fields ever assembled.
Four of the 10 fastest men ever - seven of the top 20 - including 2.03.23 world record holder and 2012 London winner Wilson Kipsang, will race at a pace that Farah hopes, but is not yet certain, he can live with.
"It's completely different, track to road," the world and Olympic 5,000 and 10,000 metres champion told a Tuesday news conference held in the shadow of Tower Bridge, the iconic halfway mark of the race.
"When I'm training normally I know I can do reps of 5km or whatever it is but for the marathon it's so much harder as you just don't run those distances very often.
"But I've learned a lot and am really looking forward to it. Now is the time to test myself and find out if I'm good at it or not."
"Good", of course, is a relative term for a man with a sound claim to be Britain's greatest-ever athlete. Such is the progress he has made over the last four years, with his superlative distance double among the highlights of the London Olympics, that expectation levels among the public have rocketed.
Farah gave them a taster a year ago when he ran the first half of the London Marathon in a bid to gain some experience and familiarise himself with the course and logistics of the race.
That went well enough, but another half-marathon outing in New York three weeks ago was not so smooth as he tripped early in the race and then collapsed unconscious after crossing the line in second place behind Kenya's Geoffrey Mutai - who is also racing on Sunday.
Farah, 31, brushed off the incident on Tuesday, saying the extra effort he had to put in to recover from his fall, combined with the cold weather, left him completely spent.
"When you go down in a race it's hard," he said, "You're already tired and it's hard mentally. I was just trying to finish hard but I was seeing stars at the end.
"It's happened before, I did it after a cross country in 2009, so I wasn't worried and I've just got a few scratches on my hip from the fall."
On Sunday Farah could face a dilemma as he tries to run the pace he thinks he can handle while possibly being drawn into a potentially disastrous breakaway if some of the African favourites, as is likely, set off at world record pace.
"I think I'll just go with the group and see what happens but I'll try to be patient," he said.
"I know with my confidence from the track I should be up there but it's the distance that's the challenge. You have to respect the distance."
Farah's presence has delivered a real buzz for home fans, who have not seen a British winner since Eamonn Martin in 1993 and fully expect Steve Jones's 29-year-old British record of 2:07.13 to fall.
Farah certainly has that mark in his sights. "That's my main target," he said. "I want to go after that British record then see what comes.
"It's going to be an incredible race, whatever happens - just look at the field."
Farah said he had taken heart from Kenenisa Bekele's 2:05.03 debut win in Paris last week as the man who preceded him as world and Olympic double distance champion chalked up the seventh fastest debut ever.
"That was a great time for his first marathon and it gives me great confidence but this is completely different to Paris," said Farah, who won London's mini-marathon three times as a teenager based in the south-west of the city having moved from Somalia as an eight-year-old.
"He had nobody there to worry about, he went in with a different mind than me in London, which is by far the toughest field."
Farah said he had no concerns about testing himself against the best, even if it meant potentially denting his reputation as a serial winner.
"Every race is a risk for me," he said. "I've gone straight in at the deep end - but that's what champions do."
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