But the heartbreak and tears on display when the two gave U.B to a local family after completing their journey showed just what his companionship meant during the tough times.

“We were so focused on the goal of covering 25km a day that having a dog eating and drinking extra supplies, Ron found that difficult to justify,” Rolston says nine months on from the final putt.

“That was totally understandable as he was the one dragging all our gear. Looking back, my decision to keep him around could well have jeopardised the expedition.

“He grew throughout the trip, becoming almost overly protective of our camp. He fought other dogs for us to the point where we had no trouble at all with village dogs. We could walk 2km into town, leaving all our gear with him and no one would touch it,” adds Rolston.

Feature film The Longest Hole, Golfing Across Mongolia premiered in Hong Kong this week and documents the pair’s journey, the impact their new friend had on them and the epic quest of a dog that is “probably 10 years old and walked the whole country”.

And there could be another chapter in the story yet, with Rolston floating the possibility of a film screening in Mongolia and a potential reunion with U.B.

“I actually get goosebumps,” says Rutland when reflecting on the mission. “I don’t think when we were actually doing it we realised how flipping difficult it was. The sheer intensity of what we set ourselves up for,” adds Rutland, who acted as caddie.

“My body is broken, I did damage to myself. I basically haven’t done anything since. I’m going for a hip replacement in two weeks time and I had to have an ankle operation.”

But there are no regrets from Rutland – he says doing it all again would be a “no-brainer” – or Rolston, who can now fully understand, both physically and mentally, the enormity of their effort.

“We drew this map across Mongolia, we had 2,000km, we had a 90-day visa so we had a time limit. We said 25km a day, that’s doable, but 25km a day on day one, two and three you can picture, but on day 50 and day 63?

“We did 2km on day one, the weather and conditions were unbelievably horrific, we were at the base camp of this peak which was a permanent glacier so we expected it to be cold, but they were some of the coldest nights of my life.”

After setting off from the base camp of Khuiten Peak – the highest and most western point in Mongolia – the pair finished on the 18th green of the Mt Bogd Golf Club in Ulan Bator, setting a world record in the process and raising US$25,000 for the Laureus Sport for Good Foundation.

Cut down from 78 hours of footage filmed by videographer Andrew King – who took about a third of the journey with the pair – and Rolston himself, the film was produced by King, Rolston, Rutland and Rolston’s brother Ed.

“We’ve kept it our own, we didn’t want to just send it to a production house,” Rolston says, adding they will use film festivals to gain traction that will hopefully see the film reach the mainstream media.

The rawness of the film carries the viewer on an emotional journey of exhaustion, long nights and debilitating pain, but for Rolston it is something more trivial that sticks in his memory.

“Ron bought the same flavour of dehydrated food for the whole trip, that just got so hard. I thought about food every single day for 80 days,” he says.

There will be another screening of the film in Hong Kong later this month.