Police are reviewing security in the Rotorua Marathon after an angry motorist forced runners into oncoming traffic.
It is the first year the marathon has been held without a police escort. Instead, organisers relied on cyclists in high-visibility vests to lead the race.
But a verbal altercation led to an angry motorist pulling on to the race course last week.
Race winner Phil Costley said he had to run into oncoming traffic to avoid the car while the driver was arguing with official race cyclists.
"The scary part of it was I made the decision to run around the car on to the road and as I did it I didn't know if he was going to pull out," Costley said.
"If he had've pulled out, he would have taken us both out."
Acting Sergeant Grant Keys from Rotorua police said the motorist had been interviewed and more witnesses were being spoken to before a decision would be made on charging anyone.
He said there would be a post-event analysis to decide if things could be done differently next year.
"It was a new process without the police escort leading the race and, unfortunately, this incident has occurred," Keys said.
"We will look at what we can improve or if this was a one-off incident."