All football managers have moments of doubt, no matter how successful they are. For Pep Guardiola, his most recent came back in March in the away dressing room at Goodison Park.
In the midst of preparing his team for a Premier League match against Everton, Manchester City's manager suddenly found himself consumed by the threat lurking on the immediate horizon across Stanley Park the following Wednesday.
'They scare me,' Guardiola said to two of his coaches. 'They are dangerous. I mean it.'
Guardiola – his words picked up by cameras filming for the recently released Amazon documentary about the club – was talking about the Liverpool attacking three of Roberto Firmino, Mohamed Salah and Sadio Mane. 'That is Liverpool,' he said. 'No more than that.'
The setting and timing of Guardiola's little outburst may have been incongruous – moments before a game against a different team – but the Spaniard's fears proved well-founded.
At Anfield in the first leg of City's Champions League quarter-final against Liverpool, Guardiola's team were shot down in a blaze of Liverpool glory. Salah scored the first goal and Mane the third. The game – the tie – was over in 31 minutes.
Almost exactly six months later, City go to Anfield again on Sunday. The threat will be identical and the challenge grows larger for City with each passing season.
City have not won at Liverpool since Nicolas Anelka scored twice in a 2-1 win in May 2003. For Guardiola the issue of how to nullify and overcome Jurgen Klopp's explosive team away from home remains the biggest nut to crack while for players like Vincent Kompany and Sergio Aguero – who has never scored at Anfield – visits to the famous old ground have begun to resemble trips to a torture chamber.
After last year's Champions League game, Guardiola bemoaned the fact that his team had made it 'so easy' for Salah in particular. But asked on Friday if he thought his players had finally learned how to defend against Liverpool's front three, Guardiola's reply was in character.
'These guys are so dangerous,' he said. 'But I always feel the same. My game is to attack better than them.
'I've never understood the idea of going to the biggest stages and just defending. We have to defend when we need to but that is not our approach. It would be boring and we didn't build the team that way. We have to be ourselves, even at Anfield.
'Salah and Firmino and Mane like to be with the ball and attack, attack, attack. To minimise that we have to attack as much as possible ourselves. If we lose, congratulatons to Jurgen [Klopp] and his players and we will have to try again.'
With City having taken top position from Liverpool after last weekend's Premier League action, Sunday's game is not short of significance. Liverpool finished a huge 25 points behind champions City last season and will definitely be closer this time.
Increasingly, there is little love lost between the two clubs. With Manchester United a fading force, Liverpool represent the greatest threat to what City hope will be a period of domestic hegemony.
Some people at City believe Liverpool are treated with too much reverence by sections of the media while on Merseyside their rivals' sudden emergence on the back of mammoth spending is viewed in some quarters as rather vulgar.
Last season's attack on the City team bus at Anfield has not helped and has not been forgotten. The lack of subsequent arrests still infuriates City, Guardiola is still riled by the whole business and suggested on Friday that Liverpool's supporters could prevent a repeat simply by 'going inside the stadium'.
'There should not be any need for the police,' he said, pointedly.
With any luck, lessons will have been learned from that episode and the intrigue and combativeness will be restricted to the field this time.
Guardiola couldn't have sold this game any better for Sky if they had presented him with a script. Once again it would appear that Sunday's game will resemble two juggernauts running into each other.
The City manager's promise to go toe to toe with Liverpool was exactly the same prior to last seaon's European game and given how that ended it is interesting to observe he will not be changing tack this time.
Guardiola's critics – and he does have some – say he won't change the way his team play simply because he doesn't know how to. His allies say that his commitment to atacking football should be hailed.
What we know for sure is that Guardiola does fear the threat carried by the Liverpool attack. City's carefully manicured documentary didn't always tell us much that was revelatory, but it told us that.