The true impact of City's staggering August win at White Hart Lane took a long time to sink in.
Looking back, it is as amazing as any other of the freak results that have littered the season given Tottenham have bounced back to become serious Premier League title contenders.
And, whilst Johnson is determined City should maintain their perfect home record, the former Middlesbrough man accepts it will be much tougher.
"That was a one-off," he said.
"We humiliated them with some of the football we played. I don't think many teams would have got close to us. The passing and movement was staggering.
"But the fact is they have some top players, a squad packed with quality, and are playing much differently now."
Still, Johnson feels there is an anxiety in the Spurs camp about their true chances of overhauling City.
After all, Rafael van der Vaart wouldn't have started to question the Blues credentials if he felt they were no good.
"It shows we must be doing something right if people are talking about us all the time," said Johnson.
"If people weren't worried they would talk about themselves, so to find time to talk about us might show we are at the back of their minds."
Johnson was speaking on a visit to Moston Fields Primary School with City team-mate Gareth Barry to promote the club's healthy eating project 'Strike a Balance', sponsored by leading north-west law firm Hill Dickinson.
After opening up a three-point lead on Manchester United and a five-point advantage over Spurs, not finishing the season as a champion would be pretty hard for Johnson to digest.
"I would be devastated if we didn't win it," he said.
"Most of lads are not thinking about it but we are three points clear, so from this position, it would be devastating not to do it."
Yet Johnson knows that City are not the neutrals' choice for a new name on the trophy.
"Maybe because we have spent so much money, people think we are trying to buy the title," he said.
"Tottenham are the team who have nothing to lose and all the pressure is on United and City.
"But the pressure is on whoever is up there to sustain it. If Tottenham do that, there will be massive pressure on them. In the last four or five games, when things are still tight, that is when we can see who will hold their nerve."
Confirmation City have accepted a bid from QPR for defender Nedum Onuoha and that Carlos Tevez's advisor Kia Joorabchian has opened preliminary discussions with Paris St Germain indicate a reshaped Blues squad will be heading out of the transfer window.
Indeed, a double departure may offer manager Roberto Mancini the funds he wants to bolster his midfield, even if the chances of landing number one target Daniele de Rossi from Roma appear to be receding.