The 35-year-old will on Sunday be bidding to become the first South African since Bruce Fordyce to win three editions of the race in a row.
But there is a strong list of more inexperienced runners hoping to beat him, including the likes of Gordon Lesetedi, Edward Mothibi and Renier Grobler.
On top of the new local kids on the comrades block, the race in 2019 will also see a seriously strong foreign contender in Japanese world 100-kilometre ultra-marathon record holder, Nao Kazami.
Other potential winners from beyond the borders include Hatiwande Nyamande of Zimbabwe and Briton Steven Way.
Mthembu concedes that it will be an open race as the athletes run upwards from Durban to Pietermaritzburg in 2019.
Mthembu has enjoyed a successful year thus far. His training has gone well and he also won the Two Oceans Marathon in Cape Town over Easter.
Not many have won that race and the comrades up-run in the same year, but Mthembu says he is not thinking too much about those things.
Bruce Fordyce is the Comrades King after dominating the race in the 1980s when he won nine times. The only man to win three in a row after him was Stephen Muzhingi of Zimbabwe.
— Bruce Fordyce (@BruceFordycerun) June 6, 2019
Now Mthembu can become the first South African to do that since Fordyce, but he was modest about the possibility of doing just that.
There was also plenty of talk from some of his rivals about chasing the up-run record of five hours, 24 minutes and 49 seconds (5:24:49) posted by Russia’s Leonid Shvetsov in 2008.
Mthembu laughed off the possibility, saying action spoke louder than words.
He added that his aim was to cross the finish line and finish the race rather than setting any records.
— Comrades Marathon (@ComradesRace) June 7, 2019
– Report by Thahir Asmal