If Horspool is seen as a latecomer, Auckland chef Ciaran Faherty, originally from Ireland, is almost a novice, having competed for only a short time.
But so far in 2016 he has impressed with wins in the New Plymouth Mountain to Surf Marathon in 2:21:58. The race is on a downhill course but the time was impressive. He also won Huntly Half Marathon in 1:09:17 in March.
The battle between these three will be intriguing, and add into the mix 2014 Auckland Marathon champion Stephen Lett from Takapuna and 2013 national championships medallist Chris Sanson from Palmerston North and the race could be fought out all the way to the finishing straight.
Mel Aitken, another relative newcomer to running, but completely dominant in masters road and cross country over the last 12 months, looks to have a good chance of taking out the women's race. The police inspector from Dunedin, currently based in Greymouth, has a personal best of 2:49:13.
Klaartje van Schie, from Palmerston North and Katie Wyrill from Auckland both have experience on the Rotorua course and have recorded placings in previous years. Liza Hunter-Galvan is also entered with a sub 2:50 timing in 2015.
Favourites for the half marathon include Rotorua teen Michael Voss, and Alice Mason from Hamilton. Both finished second in last year's race and are in good form.
The large marathon entry also includes many striving for Athletics New Zealand marathon titles for registered club athletes in the masters grades for those aged over 35.
The 52nd running of the race will be without stalwart Colin Smyth who passed away just months after completing his 50th Rotorua Marathon race at last year's event, but the Survivors Club goes on with Smyth at the top of the list.
Over 500 club members have gained membership to the Survivors Club by completing a minimum of 15 Rotorua Marathons. James Crosswell (66) from Opotiki will move up to 40 completed marathons.
Lion Foundation Rotorua Marathon will have more than 5000 participants this year. It is expected that 1450 will line up in the marathon, 1300 in the half marathon, 800 in the quarter marathon and 200 in the 5.5km.