Abbott World Marathon Majors champion Eliud Kipchoge will start as a hot favorite for Olympic gold in the Rio Games men's marathon this Sunday, when he aims to take an outright lead at the top of the Series X leaderboard.
Kipchoge produced a masterful performance in April when he smashed the Virgin Money London Marathon course record in 2:03:05, the second fastest time ever on a record legitimate course. It was the 31-year-old's sixth victory in seven marathons since 2013, a sequence that has brought him four of the best 13 times in history and saw him crowned Series IX Abbott World Marathon Majors champion.
Kipchoge now sits on top of the Series X standings with 25 points alongside this year's Boston marathon winner, Lemi Berhanu Haylu of Ethiopia, and a second victory in Rio would give him an almost unassailable lead in the 12-month, eight-race contest.
Kipchoge's London time was just eight seconds outside Dennis Kimetto's world record and in Rio he will have in his sights on Sammy Wanjiru's Olympic record of 2:06:32 from Beijing eight years ago as he aims to emulate his late compatriot by becoming the second Kenyan man to win Olympic marathon gold.
Following Jemima Sumgong's thrilling triumph in the women's race last Sunday, victory for Kipchoge would mark the first time in Olympic marathon history that athletes from the same country have won both marathon titles.
But Kipchoge will not be the only Kenyan with that aim in his mind, for he will be joined on the start line in Rio's Sambodrome by Stanley Biwott, the 2015 TCS New York City Marathon champion who lies joint third in the Series X standings after finishing second in London, and Wesley Korir who is seventh in the standings after finishing fourth in Boston.
As ever, the main threat to Kenyan dominance will come from Ethiopia, not least from Berhanu whose hard fought Boston victory came just three months after placing second at the Dubai Marathon in 2:04:33, nine seconds behind winner and compatriot Tesfaye Abera.
Abera's Dubai victory in this year's third fastest time earned him a place in his nation's Olympic team while Tokyo Marathon champion Feyisa Lelisa, Ethiopia's third man in Rio, will also have his eyes on a medal.
Lelisa was third in the BMW BERLIN Marathon last September and placed equal third overall in the Series IX AbbottWMM standings. Both he and Abera will be looking for their first points of the Series X campaign.
The favorites may come from Kenya and Ethiopia but championship marathons are notoriously unpredictable, as proved by Stephen Kiprotich whose shock victory at the London Games four years ago was only Uganda's second Olympic athletics title.
Kiprotich's outstanding championships record means he should not be overlooked as he returns to defend his Olympic crown in 2016. He went on to win world gold in 2013 after placing eighth in 2011 and was sixth at the Beijing World Championships last summer.
The man who won that race will also be one to watch in Rio. Ghirmay Ghebreslassie (Eritrea) became the youngest ever championship marathon gold medallist when he took the Beijing title aged just 19 and he followed up with an impressive fourth place at this year's London Marathon. If he wins in Rio, he will break an 84-year old record to become the youngest ever (by 40 days) Olympic marathon champion.
Another strong performance from the Eritrean could see him adding to his four Series X points while his compatriots Amanuel Mesel, who was ninth in Beijing last year, and Tewelde Estifanos, the 2015 Oita Marathon champion, could also threaten the top 10.
Runners representing Bahrain were prominent in the women's race last Sunday and Shumi Dechasa should feature among the leaders in the men's event. Dechasa broke the national record to win the Hamburg Marathon in 2014 and was fifth at the Beijing World Championships 12 months ago.
The European challenge should come from former Kenyan Kaan Kigen Özbilen, who broke the Turkish record to finish third in the Seoul Marathon in March, and Swiss record breaker Tadesse Abraham, who was fourth in Seoul and won the European half marathon title just a month ago.
Meb Keflezighi (USA) knows all about running Olympic marathons and the Athens 2004 silver medallist who was fourth at the London Games returns for a third shot at gold at the age of 41. The former Boston and New York winner leads a US team that includes London 2012 10,000m silver medallist Galen Rupp.
The presence of Brazil's two-time New York champion Marilson dos Santos on the start line should attract large crowds to the coast-hugging course for what should be another fascinating race. At 39, Dos Santos's best days may be behind him, but he was fifth at London 2012 and with strong support could be highly placed again at his home Games. He joins Kipchoge, Kiprotich and Keflezighi as the only men in the field with multiple Majors wins.
The Rio Olympic Games men's marathon starts at 09:30 local time Sunday.