Koeman and Guardiola were room-mates during their Barcelona days when the Dutchman was asked, by the late Johan Cruyff, to mentor a young Catalan midfielder who was breaking into the first team in the early 1990s
Koeman took Guardiola under his wing - the pair helped Barcelona win their first European Cup in 1992 - and to this day they are firm friends.
They will meet on the touchline at the Etihad Stadium on Saturday, and Koeman knows what to expect from a side instructed by arguably the greatest coach of his generation.
"I have all good memories of Pep
We have a really strong friendship
Now it's a bit easier because he's living in Manchester and I live close to Manchester," said the Everton boss.
"Sometimes we have time for dinner and to talk about football and to talk about life
But of course we have spent many hours together talking about football.
"When he was manager of Barcelona I saw the best Barcelona team in every aspect of football.
"The standard there was, and is, always high but he made it 200 per cent in every aspect of football.
"We like to see a team play attractive football, who likes to dominate
Sometimes that's risky what they try to do but that's football that I like
"Of course everything is about winning at the weekend but he is doing it in the most difficult way as a manager.
"Most of the other managers win titles but not with that way of football.
"City have been very good - maybe not the last week before international duty (when they drew 3-3 with Celtic and suffered their first defeat of the season at Tottenham) - but it is impressive the way they play football.
"I watched them against Borussia Monchengladbach in the Champions League live and it was a good job to see the difference between how they play this season and how they played last season.
"It's difficult to defend against but we have had some good examples of teams getting a good result against City."
With Koeman focused on a return to Premier League action he was unhappy with Republic of Ireland's handling of James McCarthy.
The midfielder departed for international duty having not featured since August 23 because of a groin injury which required surgery, and his manager expressing hopes he would be "protected".
He returned to the club's Finch Farm training ground having completed 90 minutes against Georgia last Thursday and 81 minutes against Moldova on Sunday.
"I know he played the full game after three group sessions with Ireland and then he played the second game and is massively over-loaded," said the unhappy Dutchman.
"We have to make a decision tomorrow if he's really fit to be part of the team."
Koeman had better news over his other injury concerns with Romelu Lukaku, Phil Jagielka and Leighton Baines all fit for the weekend.
Striker Lukaku had reported an issue with his thigh after Belgium's World Cup qualifier last week, while Jagielka pulled out of England's squad with a similar problem
Baines missed the previous two matches with a hamstring strain
Source : PA
Source: PA