Daily Lay: David Rudisha in Men's 800m at 2.265/4
It seems sacrilegious to suggest laying an athletic deity - especially one who I predicted would break the world record in London 2012 - but David Rudisha has not shown the form in recent seasons that suggests he is capable of retaining his Olympic title here. He has struggled with a knee injury in the last couple of years, and although he has appeared healthy this season, the psychological dominance he held over his rivals is a thing of the past: he is now rarely given his own way out front, instead being harried and, more usually in recent races, failing to cope with it.
His short odds are wholly a result of him running a world-leading time of 1.43.35 last month, which signalled to some that he is back to his best. There have to be doubts, though - especially as Rudisha only managed third in the Kenyan trials behind the 19-year-old Alfred Kipketer - and in what will likely be a series of tactical races, Rudisha will struggle, and it wouldn't be a huge surprise if he fails to qualify for the final.
Daily Play: Almaz Ayana in Women's 10,000m at 1.351/3
The first gold medal on the track should go comfortably to Almaz Ayana. To those who only watch athletics once every four years, there may be some surprise as to how a runner can be such short odds when taking on Tirunesh Dibaba, a three-time Olympic champion, five-time World champion, world-record holder in the 5,000m, and all-round running legend.
But since the last Olympic Games, Almaz Ayana has happened. She came into the athletic consciousness when claiming bronze in the World Championship 5,000m in 2013. Since then she has been dominant. In the last two seasons she has comfortably topped the world-best lists in 3,000m and 5,000m, and this year has added the 10,000m to that, running the eighth-best time of all time in Hengelo at the end of June. She is still only 24-years-old and can improve further. Expect her to hit the front with a few laps to go, setting split times that no one else will be able to live with: provided she is healthy and nothing calamitous happens, it's hard to see her losing.