Thun's extraordinary run has left the likes of Young Boys and defending champions Basel trailing in their wake.
Comparisons have been made with newly-promoted Kaiserslautern winning the Bundesliga in 1998, Leicester City lifting the Premier League trophy in 2016 or Mjallby, a team from a fishing village, winning the Swedish title last year.
According to Transfermarkt, the Thun squad has the second-lowest market value in the 12-team Swiss Super League, at 16 million euros ($19 million) - way below Young Boys at 67 million euros.
Thun won promotion from the Challenge League last season, ending a five-year spell in the Swiss second tier.
And after 22 matches back in the top flight, Thun are nine points ahead of second-placed Lugano, with St. Gallen, Basel and Sion trailing further behind.
They have scored the most goals and conceded the joint-fewest.
History favours their chances of lifting the trophy: Swiss public broadcaster SRF said that since the Super League era began in 2003-04, no team has ever squandered such a lead at this stage of the season.
Secret to success
Cementing their dominance, Thun won 2-1 at Basel on Sunday, deflating the 26,000-strong crowd at St. Jakob-Park.
"The championship title is still a long way off," manager Mauro Lustrinelli told SRF afterwards, sounding a note of caution.
With 16 matches to go, Thun travel to Geneva to face struggling Servette on Sunday.
Thun's home is the smart-looking, 10,000-capacity Stockhorn Arena. The stadium and its artificial turf hosted three matches during the last year's women's European championships.
Thun's 2009-10 and 2024-25 second division titles are the biggest honours the club has won since its foundation in 1898.
But excitement is building in the Bernese Oberland at the prospect of the Swiss title coming to Thun, a German-speaking lakeside town of 45,000 people dominated by its castle.
In a message to supporters on Thun's website, club president Andres Gerber, a former Thun captain and Swiss international, said it was difficult to explain "the secret of our success".
But a team ethic, plus "a successful mix of humanity, professionalism, expertise, money and, above all, lived continuity, is crucial".
"I believe and feel that this mix is right at FC Thun today - both on the pitch and in the entire club."
Efficiency and continuity
Lustrinelli, 49, is a Thun legend, providing, like Gerber, continuity from the club's previous peak.
He scored 20 goals for Thun in 2004-05, driving them to second in the Super League - hitherto their best-ever finish.
The club went on to play in the UEFA Champions League group stage where they finished third in their group behind Arsenal and Ajax but ahead of Sparta Prague.
The former Switzerland striker, who featured at the 2006 World Cup, took the manager's job at Thun in 2022.
Lustrinelli has quietly forged a close-knit unit without superstars, building a team that doesn't necessarily dominate every game but is exceptionally efficient in its approach.
Players such as midfielder Leonardo Bertone, 31, seen as a Swiss David Beckham for his charisma and free kicks, exemplify the blend of talent, team spirit and clear tactics.
Winning the Swiss second division and then the first division back-to-back has only been done once before: Grasshopper Zurich, Switzerland's most decorated team, completed the feat in 1952.
"I'm not at all worried about us getting carried away," midfielder Valmir Matoshi told SRF after scoring the winner at Basel.
"We're from Thun, we're down-to-earth. And we're slowly getting used to winning."
