In two-and-a-half years as Latvia's national coach and technical director, Johnson mixed it in World Cup and European Championship qualifiers with the likes of Norway, Georgia and Belgium, experienced the intimidation of a match in front of 50,000 in war-torn Croatia and lost 1-0 to Scotland in Riga after a goal in the 89th minute.
He knows all about squeezing the most out of limited resources against superior opposition. Which is why Liverpool's under-achievers could be in for the fright of their lives against the Nationwide League's newest side in Sunday's intriguing tie at Huish Park.
Johnson's Latvian adventure came about when he was head-hunted while assisting former England manager Graham Taylor at Watford in 1999. In what sounds like something from a spy thriller, he was approached by a Russian agent who set up a meeting at the Dorchester Hotel in London with Guntis Indriksons, the president of the Latvian Football Association.
Johnson was invited to Moscow to identify Latvian talent who might make it in English football and was instrumental in bringing Marian Pahars to Southampton.
"I was king of Latvia for a while after that," says Johnson, who took the job as national coach where he was supplied with a Russian interpreter. "My brief was to get Latvia players into the European football scene and Latvia onto Europe's football map.
"They were very Russian at the time with a sweeper system. I changed the philosophy to going out to win a game rather than simply trying not to lose. I brought flair players to the fore."
Johnson also brought some sharp Cockney wit to the Latvian training ground and by the time he had completed his two-and-a-half-year stint, to keep a promise to his wife Caron to return home, he had also gained experience at the highest level which he has utilised to Yeovil's benefit.
Not only did he guide the Somerset club with some style into the Football League for the first time in their history, but he has gathered together a precocious squad with an average age of 23 and a raging ambition to succeed.
Currently they stand fifth in the Third Division, on course for promotion despite successive losses against Kidderminster and Swansea, yet with a fearless attitude towards their clash with Liverpool.
"More than anything I think what my time with Latvia has brought is a mentality and philosophy that's higher than this level," said Johnson. "I've made all the players move into the Yeovil area and I've still got 18 of the 22 players who were with us in the Conference. They're young and ambitious.
"We like to play football, five-yard passes as well as 50-yard passes. There's a right ball at the right time, it's about quality and having a purpose. You'd say we should have less than no chance against Liverpool but the nature of the beast at this club is that the players won't let themselves even think that.
"We want to win. I won't say, 'Go out there lads and just enjoy it.' That's not what we are about. If these lads are playing tiddlywinks or Liverpool in the cup they want to win. They are so focused."
They are also aware of the giant-killing history at a club which as a non-league outfit took 20 League scalps and who in 1949 beat Sunderland, then one of English football's mighty forces, on their own ground before losing in the fifth round to Manchester United.
"Now we want to create our own new reputation and guard it with our lives," says Johnson. "In 60 or 70 years time I want a bust of me to be outside the ground because it means I will have created something. I subscribe to the old adage, the harder I work the luckier I get." Johnson talks a good game and his squad boasts Hugo Rodriguez, at 6ft 8ins the tallest player in the league, plus the manager's son Lee a stylish 22-year-old midfielder who was on the books at Arsenal and Watford but whose dad persuaded him against a career in Denmark in favour of joining him at Yeovil.
They can promise Liverpool the most intimidating of atmospheres, a work ethic second to none and the good wishes of everyone in Latvia, where Johnson was invited last summer as guest of honour at the Eurovision Song Contest to see Britain embarrassingly score 'nul points'. Liverpool must guard against the same fate in giant-killing country.