"Unfortunately three days before the race I came down with a virus and on the Friday before the race I wasn't able to eat or even have enough strength to walk," said Wreford.
"It was silly to try and start, especially when I wanted to vomit in my warm-up for the race. I am a fighter and don't like giving up but I have learnt my lesson and common sense does need to be used."
After his "bad mistake", Wreford ended up having a break from all running for about eight to 10 weeks to recover. He came back in style, claiming the title at the Auckland Marathon in October.
Fast-forward to today and Wreford is once again chipper and confident of his chances of claiming a second title in the race that he has a special connection with.
"I am very happy with my build-up for the Christchurch Marathon and it has been indicating that I am stronger than ever before, so it gives me great confidence heading into this race.
"Even though I live in Timaru, it feels like my hometown marathon.
"I grew up being inspired by watching Phil Costley and Jonathan Wyatt running very fast times in the half, and Phil also in the full and thinking I would like to compete in this event, although I can only dream of running as fast as they did."
Even though the course has changed since those days, Wreford has run almost as fast as his heroes.
When he claimed the title in 2012, he smashed his personal best time and completed the then-new course around Christchurch Airport in 2hr 17min 3sec in perfect conditions.
He took 1min 48sec off his previous best, which was set in the Dunedin Marathon, and he beat runner-up Dale Warrander by more than five minutes. "It was very special for me because after so many years of being prevented from running the half or full due to injury, I finally got to race for the first time and to win was a great feeling."
He expects tough competition from Australian Nathan Hartigan - who finished fourth in the half-marathon at Christchurch last year in an impressive time of 1hr 6min 15sec - and others.
"Tony Payne was unlucky to have a hamstring problem in the Rotorua Marathon a few weeks ago which cost him a possible chance of winning, and Stephen Lett, who I defeated at the Auckland Marathon, is also a very tough runner."
He knows that he will be rated by many as the favourite.
But he also knows that won't count for much on the day.
"I don't put any pressure on myself as that wrecks the enjoyment of running. When you just relax and let things happen the results will come."
When he is finished, whatever his result, Wreford loves hanging around the finish line to be inspired by the efforts of the weekend warriors.
"The great thing about running is that no matter what your ability, everyone can have their own personal goal and if you achieve that you can have as much satisfaction as anyone else."
About 5000 runners are expected for the Christchurch Airport Marathon and they will experience what could be a first in New Zealand.
As a special favour for the final year on the airport course, Christchurch Airport has gained permission for competitors to run on the airfield on the final approach to the finish line.
"This is a rare treat and we're not even sure it has been done in New Zealand before at an international airport," said the airport's chief operating officer Andy Lester.
Following the Christchurch earthquakes, the race was forced away from its traditional course in the central city. First it went to Lincoln for a year and then to a course hosted by the event's principal sponsor, Christchurch Airport.
The event organisers and airport are working with Christchurch City Council to return the race to a traditional city course next year.
Race director Chris Cox says including the airfield will make the event a fond farewell to this part of town. "Christchurch Airport's willingness to host the marathon played a big part in the event's fast recovery after the earthquakes," said Cox. "Being able to actually run on the airfield this year is another great initiative from them."
The Christchurch Marathon has played a significant role in the recovery of the city. It generates more than $2 million in economic gain, thanks to more than 1000 visitors from 12 countries and all ends of New Zealand who arrive to participate.
The Christchurch Marathon offers a full marathon, half-marathon, 10km run and the kids' mara'fun. "Our only real goal over the years has been for it to be a reflection of the community," said Lester. "We have the country's best runners right through to people taking to the sport for the first time."
