The gut-busting combat event has different stages which include climbing a tower, hauling hoses, hitting a weight with a hammer, shooting a disc and hauling 'Rescue Randy' (an 82kg dummy) to the finish line.
Competitors are in full firefighting kit and have to be extremely fit.
Bestwick has been training hard for the event combining gym work and a variety of course-related activities.
He will literally be flying the New Zealand flag at the World Firefighter Combat Challenge.
The local firefighter has a specially painted helmet to help him stand out from over 1000 firefighters taking part.
"Our team of three have all had their helmets painted by Dean Lorich of Beachlands, he has done a great job and we thank him for that.
"Thanks also go to the Te Awamutu Fire Brigade for their support and to my employers Gold Pine for allowing me to compete."
Bestwick, Warren Maslin from Ashburton (40+ NZ title holder) and Stu Goodhew from Edgecombe (2nd in NZ 50+) are combining for the event. They will all run the individual, tandem and relay team events.