The big favourite – on the basis that he has won the past three world titles and was the 2008 Olympic champion – has to be Asbel Kiprop.
The Kenyan has been in outstanding form this season with the one notable exception of his last outing at the IAAF Diamond League meeting in Monaco.
He clocked a world-leading 3:29.33 when winning at the IAAF Diamond League meeting in Birmingham two months ago and won in Doha as well as over a mile in Eugene and Oslo.
However, a dramatically misjudged race in Monaco, when he finished sixth in a race won by his Rio-bound compatriot Ronald Kwemoi, who clocked 3:30.49 to go second on the 2016 list, has given his rivals hope despite the fact that it has been his only loss in eight outings over 1500m or a mile this year.
Kwemoi, the Commonwealth silver medallist, is still only 20 and set a world U20 record of 3:28.81 in Monaco two years ago.
His career seemed to stagnate slightly last year and he even finished out of the medals at the African Games, a consolation prize for not making the IAAF World Championships Beijing 2015 team, but the Japan-based runner is clearly back on track.
Before his eye-catching win in Monaco, Kwemoi clinched his place on the plane to Rio by finishing third at the Kenyan Olympic Trials behind Kiprop and world silver medallist Elijah Manangoi, who additionally had to settle for second place in Monaco.
With Manangoi crossing the line in Monaco in 3:31.19 for third place on the 2016 world list, the thought has crossed a few pundits’ minds that Kenya might become the first nation to take a clean sweep of the 1500m medals in the history of the Olympic Games.
Paramount among the men who will try to stop them is Algeria’s defending champion Taoufik Makhloufi, who showed he is in good shape by finishing third in Monaco.
But Makhloufi may have a hard decision to make.
He is also entered in the 800m and has advertised his intention to double, but the Rio programme is not too sympathetic to such ambitions with the final of the 800m late on the night before the 1500m heats.
Also entered for another event in addition to the 1500m is 2012 world indoor champion and Olympic bronze medallist Abdalaati Iguider.
However, Iguider – who ran a 1500m season’s best of 3:31.54 for fourth place in the deep Monaco race – is also entered for the 5000m and at these championships it is impossible to run both so it is expected that the Moroccan will likely to focus on the shorter event.
Djibouti’s one and only Olympic medal in any sport came in the men’s marathon back in 1988, but 2014 world indoor 1500m champion Ayanleh Souleiman has shown good enough form this summer to possibly be capable of adding to that meagre tally.
The only potential problem for Souleiman is that, like Makhloufi, he is also entered in the 800m, the distance at which he won the world bronze medal in 2013.
The prevailing feeling is that doubling over 800m and 1500m in Rio, due to the programme, might be slightly detrimental to a runner’s medal hopes in contrast to if he had concentrated on just one event, although Makhloufi and Souleiman have the pedigree to take on both events without too many difficulties.
It seems unlikely that the 1500m medals will be won by anyone from outside of Africa, but USA’s Matt Centrowitz has proved adept at confounding that theory in recent years and the US champion is back again to lead the challenge from the rest of the world.
Another non-African to keep an eye on is Norway’s European champion Filip Ingebrigtsen, who possesses a devastating turn of speed over the final 150 metres, which may just cause a surprise if he is in a slow-run final.
Phil Minshull for the IAAF