The task of Chumba, a winner in 2014 and 2018, has been made easier by the withdrawal from a race with a field of 30,000 of Ethiopia's three-time Olympic gold medallist Kenenisa Bekele through illness.

As well as completing a hat-trick of victories, Chumba has also set himself the target of breaking the course record of 2 hours 3min 58sec set by another Kenyan, Wilson Kipsang, in 2017. 

Chumba's fastest time of his career so far was 2:04:32, set at the 2014 Chicago Marathon.

The men’s field contains three other runners with personal bests faster than 2:05, including Ethiopia's Birhanu Legese, who recorded 2:04:15 on his debut at the 2018 Dubai Marathon, and Bahrain's El Hassan El Abbassi, who set an Asian record of 2:04:43 in Valencia last year.

Another Ethiopian, Seifu Tura, clocked 2:04:44 at last year's Dubai Marathon.

One athlete aiming to rub shoulders with that group in a race that more than 330,000 people applied to run will be Japan’s own Suguru Osako. 

There is perhaps no runner in the field whose upward curve has been steeper.

Osako set a new national record of 2:05:50 at the Chicago Marathon last year October, slicing well over a minute off his previous personal best 

Osako’s third place in the Windy City last October means he can go joint top with a second-place finish or take a clear lead in the WMM, a championship-style competition comprising six annual races in Boston, London, Berlin, Chicago and New York City, as well as Tokyo, if he tastes victory in the shadow of the Imperial Palace.

He may not be alone as far as Japanese contenders for the podium are concerned. 

Tokyo Marathon race director Tad Hayano said: "I am determined to do everything possible for the race so that at least five Japanese will run [a] 2:06 marathon before the 2020 Tokyo Olympics."

In the women’s elite field, this could be Ruti Aga’s time to finally climb on to the top step of a Majors podium. 

The 25-year-old Ethiopian came second behind team-mate Birhane Dibaba last year and has two consecutive second places from the Berlin Marathon.

Aga’s personal best of 2:18:34 makes her the fastest woman on paper and favorite to shed the bridesmaid tag, but she will face the experienced campaigner Florence Kiplagat from Kenya, who knows that winning feeling well. 

Two victories in Berlin, two in Chicago and a string of top-10 finishes in London make Kiplagat a formidable big race competitor as she aims to collect her fourth WMM star. 

Also in the field is Kenya's reigning world champion Rose Chelimo, whose nous in a tactical race will make her a contender.

If Aga wins, it will send her top of the WMM leaderboard with 41 points, which was enough last year for Kenya's Mary Keitany to claim the series title.

In the men’s wheelchair series, the United States' Daniel Romanchuk has blown the men’s contest apart with his back-to-back victories in the Chicago and New York City Marathons. 

The 20-year-old displayed both the acumen and the strength to beat Switzerland's reigning series champion Marcel Hug to the line on both occasions in that American double. 

Few backed Hiroyuki Yamamoto for victory in 2018, even less that we would see a Japanese one-two, but the 52-year-old shocked the world when he won a head-to-head sprint with Tomoki Suzuki to claim first place last year.

The women’s wheelchair leaderboard sports the familiar sight of the Swiss flag at the top. 

Manuela Schär has led from day one, with three consecutive victories and one bonus point win, to carry a 58-point lead over the US's Susannah Scaroni.

Tokyo proved a happy hunting ground for the 34-year-old Schär 12 months ago as she cruised to victory by a distance.