Johannesburg - Comrades organisers are worried that roadworks around the city of Pietermaritzburg may affect the beginning of Sunday’s race.
They warned all runners on Thursday to leave early for the City Hall.
"The roadworks are a major problem. On the freeway heading into the city, there are major roadworks going on and the fear is we’re going to have quite a bit of congestion on race day," race director Johan van Staden said.
"So we just want to send out a fair warning to all the runners to be there early and give themselves at least an hour's extra journey time to get to the start."
Extensive road works have been ongoing for several months on the main N3 route in and out of the city, with parts of the highway even reduced to a single lane.
The 87th edition of the race takes place between Pietermaritzburg and Durban over the weekend, when more than 19 000 athletes will take up the "down-run" challenge.
Van Staden said: "We will not wait for anyone. Comrades is not a race that can delay the start and our gun will go off at 5:30am, whether the athletes are there or not."
The race will be run on exactly the same route as the 2010 one, meaning it will conclude at Kingsmead.
Van Staden eased security fears for runners, saying: "We are in full compliance with the new Events Act. All our runners can relax and have nothing to fear."
Sixty doctors would be on duty throughout the day, with 300 physiotherapists expected to be stationed at nine strategic points along the 89.2km route.
At this stage, it appeared that the weather would be clear on the day of race.
"It is winter at present, but the forecast is clear for the day. We’re expecting it to be very hot and advise runners to take in a lot of liquids."
Zimbabwean Stephen Muzhingi is the three-time defending champion in the men’s event, while the 2011 women’s winner was Russia’s Elena Nurgalieva won it for the second time in succession, claiming her sixth title.