Tearney is relatively unknown among local tennis fans, lacking the profile of Michael Venus, Rubin Statham, Artem Sitak and Marcus Daniell.
He had played some tour events in 2008 and 2009 before taking up an offer from Pepperdine University in Southern California.
"Coming from New Zealand, I didn't think I was ready for the tour," said Tearney. "I didn't have the matches or exposure."
The daily diet of training and playing took care of that, as he shared a house with four team-mates and played in front of crowds of up to 5000.
There were also five-star hotels when the team travelled, as well as trainers, doctors and physiotherapists on hand. Unsurprisingly, it was a shock when he returned to the realities of the tour post-graduation.
"I remember playing in Turkey with no one watching," said Tearney. "We were miles from anywhere and I was staying in a shack. But that is what you have to do. It makes you stronger."
He says life on the Futures tour - the bottom rung of the tiered ATP system - is "pretty grim at times" but also makes for some memorable experiences.
"One in Indonesia stands out," said Tearney. "Indoor courts, tropical heat and no air con. And there were lizards in the shower.
"It's all part of the challenge but over the next year, I want to be more at Challenger level."
After a comeback from shoulder surgery in mid-2014 which had threatened to end his career, Tearney puts his 2015 success down to being "a bit more professional" in terms of diet, training habits and lifestyle. He's also gained valuable input from his coaches Clint Packer and Will Ward, with Ward even providing accommodation in Auckland.
"They are the biggest reasons for my success," said Tearney. "Clint has travelled with me sometimes and is always available for a chat and Will has given up hours of his time."
Despite his ascension to New Zealand No 1, Tearney doesn't receive funding from Tennis NZ, who target their limited budget towards juniors and the Davis Cup programme. He estimates that prizemoney has covered about 20 per cent of his costs this year, with the shortfall being made up from family support and some creative fundraising solutions, including $12,000 raised from a crowd funding page.
"It's not great to be depending on your parents at 25," said Tearney. "My goal this year is to be financially independent, and be in bigger tournaments. If I'm good enough, I'll make it. If not, well, I've given it my best shot."
That journey starts this week at the New Zealand national championships, with the prize a wildcard into the men's ASB Classic for the winner. Venus took the golden ticket last year and then enjoyed a historic first round win.
"It's a big opportunity," said Tearney. "I've always looked up to guys like Mike [Venus] and Rubin [Statham] but we all know what is at stake this week."
