"We can speak the triathlon terms, but I still don't know what he does," chuckles Barfoot, whose real estate business is also the principal sponsor for the World Masters Games.
"There are so few of us left in the 80 age group, you can track them all. I've been tracking him for two years and can tell you all his results.
"That's been a great spur to my training - I've been doing a lot of swimming, a lot of biking and as many runs as my artificial hip will let me - and I'll be giving it my all on Saturday week.
"But Boris is also staying with me and I want him to be happy, so maybe I won't mind if he beats me again."
Barfoot is legendary within the triathlon community, but hasn't limited himself to just that discipline for these Games. He will contest a variety of other events, including the half-marathon and 5000 metres in athletics, cycling time trial and open water swim.
When he's not competing, he'll have his hands full, presenting medals.
"This is my first Masters Games, but I've been to a lot of world masters championships in triathlon," he says.
"We had the opportunity to become sponsors, and it fitted in with work and play. I can do a lot of [training and competing] on the boss's time, because it's work and I'm enjoying it.
"I guess you can call me competitive - I'm competitive in my business and I'm competitive here."
Barfoot and Kirilov were among the first participants through the doors, when the World Masters Games accreditation centre opened on Sunday. Organisers found hundreds of athletes, officials and supporters eagerly waiting for the 2pm start, but the backlog was quickly cleared.
"We've been waiting for four years now for the accreditation centre to open and it's gone really well," says WMG2017 chief executive Jennah Wootten. "It's been amazing seeing so many people from all over the world, coming down to Queen's Wharf to pick up everything they need for the Games.
"We've known they were coming from 100 different countries, but today we saw that first hand. There were a number I spoke to from Italy, Finland and Argentina.
"They've been blown away by what they've seen of Auckland so far, and you can see their excitement and enthusiasm.
"The next few days are all about making sure our 28,000 athletes are well equipped with everything they need to compete in their chosen sports, so they are feeling comfortable and confident by that first day of play."
Accreditation will continue right up until Friday evening (April 21), when the official opening ceremony will take place at Eden Park. The Games run across 28 sports and wind up on Sunday, April 30.
