The Abbott World Marathon Majors professional series resumes this Sunday at 9:30 am local time, with the Olympic women's marathon in Rio de Janeiro where Series X co-leader Jemima Jelagat Sumgong seeks to make Games history for Kenya with her second victory of the year.
Sumgong won a dramatic race at this year's Virgin Money London Marathon when she recovered from a fall to defeat defending champion Tigist Tufa and take 25 points in the 12-month, eight-race contest to find the best male and female marathon runners in the world.
In Rio Sumgong aims to become Kenya's first ever Olympic women's marathon champion and move clear of the field at the top of the Series X leaderboard. Victory would put Sumgong on 50 points and set her on course for the title.
The 31-year-old was fourth at the Beijing World Championships last summer and will start as one of the favorites for Olympic gold alongside her compatriots Helah Kiprop and Visiline Jepkesho.
Kiprop won this year's Tokyo Marathon to place third in the Series IX standings after winning world silver in Beijing, while Jepkesho is the 2016 Paris Marathon champion.
The three Kenyans face formidable opposition from a trio of talented Ethiopians all capable of following in the footsteps of London 2012 Olympic champion Tiki Gelana.
Current world champion, Mare Dibaba, 2015 London Marathon champion, Tufa, and this year's BAA Boston Marathon runner-up, Tirfi Tsegaye, all have serious prospects of finishing among the medals.
Tufa and Tsegaye currently lie third in the Series X standings behind Sumgong and Boston Marathon winner Atsede Baysa, and either could move to the top with a podium finish on Sunday.
As for Dibaba, this will be her first race in Series X and the 26-year-old will be looking to get points on the board after just missing out on the Series IX winners' prize. She finished 22nd at the London Olympics four years ago but showed great strength and determination when she took world gold in Beijing with the narrowest of victories over Kiprop.
On paper, Tsegaye is the quickest of the six east Africans with her personal best of 2:19:41 from victory at this January's Dubai Marathon, but Olympic marathons are rarely won by the fastest in the field and Rio's loop course along Guanabara Bay may well yield a victor from a non-African nation.
That in itself would provide a piece of Series history for African women have won every World Marathon Majors race since the Bank of America Chicago Marathon in October 2009, a streak of 40 consecutive victories, and they've dominated the 62 events since the Series began in 2006, winning 49 of them.
Two who could end this streak have won major Asian marathons this year, Eunice Jepkirui Kirwa (Nagoya) and Rose Chelimo (Seoul). Ironically both were Kenyan born, but have switched national allegiance to Bahrain, an Asian nation.
Olympic marathons tend to have a flavor all of their own, however, and no country has a better Games pedigree at this event than Japan whose Naoko Takahashi and Mizuki Noguchi won back-to-back golds in Sydney 2000 and Athens 2004, while Europe has produced three Olympic marathon champions since women first contested the event at Los Angeles in 1984.
Japan's chances in Rio rest with Kayoko Fukushi, the Moscow 2013 World Championship bronze medalist, and Mai Ito, who was seventh at the Beijing Worlds last summer.
Portugal also has Olympic history following Rosa Mota's victory at the Seoul 1988 Games, and in Jessica Augusto, Ana Dulce Felix and Sara Moreira they have three runners capable of creeping into the Rio medal places.
Thirty-nine-year-old Jelena Prokopcuka will be another European to keep an eye on. The Latvian veteran already has AbbottWMM Series X points on the board after placing fourth in Boston this April. Volha Mazuronak also has four points to her name after placing fourth in London and she has an outside chance of claiming a medal for Belarus.
Christelle Daunay is the sole French runner in the race. She won the 2014 European Championship title on a tough course in Zurich.
Shalane Flanagan flies the flag for USA for whom Joan Benoit won the first Olympic women's marathon 32 years ago. Flanagan was an Olympic 10,000m bronze medalist in 2008 and has finished on the podium in New York and Berlin since she first moved up to the marathon in 2010.
Some 170 runners from 80 countries will contest the Rio Olympic Games women's marathon. The winner is virtually guaranteed to smash through a major benchmark. No woman has ever broken 2:30 on South American soil (record 2:30:52, Santiago, Chile) and even in a tactical race, this barrier should be shattered. The Olympic Games record is 2:23:07 by Gelana in 2012.
The Olympic Games men's marathon is on Sunday Aug. 21.