Jose Mourinho says Manchester City have spent 'very, very well' during the summer transfer window

The Sky Blues have been this summer's big spenders

Mourinho is positioning himself at Chelsea as a teacher (EPA)

When he was manager of Chelsea the first time around, Jose Mourinho would often lecture reporters on the folly of believing that his club’s success, especially in his first two seasons, was the sole consequence of the millions that were poured into it by Roman Abramovich to buy players.

What he meant, of course, was that the key reason they were dominating English football in those two seasons was their manager.

At the time, it was a difficult call. Undoubtedly Mourinho was a phenomenal coach but his meticulous planning and bold tactical calls were backed up by a level of investment in the Chelsea squad that was unparalleled in English football. The temptation was to give him most of the credit but always there was that nagging concern that there was no precedent by which to measure him and his club. The Chelsea of that era were a unique concept.

In the time between Mourinho’s departure and return, Manchester City have entered the equation. From the moment that Sheikh Mansour gained control of the club at the end of the 2008 summer transfer window – signing Robinho from under Chelsea’s noses, the player upon whom the then-manager Luiz Felipe Scolari had pinned so much hope – there has been a comparison of sorts.

At both clubs the investment has been phenomenal, although clearly there cannot be exact comparisons drawn. Wages and transfer fees had increased dramatically in the five years between the two takeovers. Mansour inherited a manager in Mark Hughes, just as Abramovich did at Chelsea with Claudio Ranieri. City replaced him and eventually won the title with his successor Roberto Mancini just as Chelsea had done with Mourinho. But Mourinho’s two titles were won immediately and after him Carlo Ancelotti won another in 2010.

The Premier League landscape for Chelsea in 2004, when Mourinho took over after a year of already significant investment from Abramovich, was very different. Arsenal were the champions, unbeaten in the previous season. Manchester United were at the end of the first season of their leanest period in the league under Sir Alex Ferguson, post-1993. Liverpool were arguably at their strongest since 1990; they were, after all, European champions at the end of the 2004-2005 season.

For City, when Mansour took over, the situation was more difficult. In 2008, United were reigning European champions with Cristiano Ronaldo approaching the height of his powers. Chelsea had benefited from five years of Abramovich investment and were by then a major European force, runners-up in the Champions League that season, their best-ever finish in the competition at that point. Liverpool would finish second in the Premier League the following May, just four points off the title. Only Arsenal by then had slipped.

In 2008, Mansour had bought a club that finished ninth the previous season. They finished one place worse off the following May. When Abramovich bought Chelsea near the start of the 2003 summer transfer window they had finished fourth the previous season and gained a place in the Champions League qualifiers. Comparisons between the two often fail to take into account the different starting points for both takeovers.

At different times in his first spell at the club Mourinho dealt with the challenge from his key rivals United, Arsenal and Liverpool. Those clubs are not as strong now as they were at certain points in his first spell at Chelsea, although Tottenham are a far better side than they were then. But City are a different beast. He has not had to face the club that was built up in much the same way as Chelsea with heavy initial investment from a multi-billionaire owner who, unlike Abramovich five years earlier, had to spend quickly before Uefa financial fair play restricted him.

It has been intriguing to hear Mourinho on the City threat. Today he characterised their signings so far this summer, Fernandinho, Jesus Navas, Alvaro Negredo and Stevan Jovetic – the investment already tops £90m – as players who are in his words “ more than ready” to play. As for his signings, Andre Schurrle, Mario Van Ginkel, Mark Schwarzer, £27m in total, Mourinho sees them differently. Schurrle and Van Ginkel, as well as some of his returning loanees Romelu Lukaku and Tomas Kalas, are players that require developing.

Naturally, he does not take into account how heavily Chelsea outspent City last summer, when the likes of Eden Hazard and Oscar arrived, and even this summer the balance will change if Wayne Rooney arrives from Manchester United. But from what he has said so far the expectation is that the Mourinho narrative on City will run something like this: they are buying the finished product, while we are investing in promising kids.

Asked about City, Mourinho said: “I know the players they've bought. Jovetic I know from my Italian time, we were in the same league for two years. The guys coming from Spain, Navas and Negredo, the same. I was three years in the league where they were. Fernandinho I've known for a long time even if I didn't work in the same country as him. I think they are players without surprises. They are more than ready.

 “If you see their age, their maturity, they are in the perfect moment of their career to go to England, no need for adaptation, no need of work to learn the project. They are players at the top of their careers, experienced but still young, so I think they've bought very, very well.

“Young players are not at the best they will be. They need to learn, they need time to get to the top. You are talking about Navas and Negredo, they are two world champions, two European champions. They are two boys of 27. Jovetic, for more than two years, is one of the best in Italian football. Again, a kid that has five years at Fiorentina, playing in Serie A at the highest level.

“Fernandinho is more than that, because he has more experience, a national team player, big experience. So they bought very, very well. That doesn't surprise me, because they have the money to buy but also the knowledge. They have people in the club that know a lot about football.”

Listening to Mourinho this last week, he makes no secret of the fact he is positioning himself this time around at Chelsea as a teacher, possibly even when it comes to players like Hazard and Oscar – the latter joins up with the squad on Sunday – who have already had a season in the Premier League and joined for substantial fees. Mourinho has also been keen to point out that he does not simply craft teams out of famous, established players bought at great expense.

“Any time I had in my hands young players with conditions [the potential] to become top players and play for the first team ... I did it,” he said. “I did it everywhere. In Porto, Carlos Alberto is still the youngest player to score a goal in a Champions League final [at 19 in 2004].

“In Italy - and maybe you don't know the best one; I'm speaking about [Davide] Santon, who is at Newcastle. Santon had two big, big injuries. But at 17 years of age everybody was saying in Italy that he should be for Inter what [Paolo] Maldini was for Milan. The kid started play with me at 17. At 17 he was playing Manchester United in the last-16 of the Champions League.

“Another kid, at Real Madrid, [Raphael] Varane [picked] in front of everybody else at 17 years old. Here [Chelsea] John Obi Mikel arrived at 18 and Claude Makelele was on the bench. Any time I have [young players], I'm not afraid to go for it.”

Asked about his part in the development of Mario Balotelli, the player he once described at Inter as “unmanageable”, Mourinho was less keen to take credit. “Balotelli started with Mancini, before me,” he said. “It was Mancini that played Mario in the first team before me.”

Mourinho has naturally been measured against David Moyes, the manager who was preferred ahead of him to succeed Ferguson at United. His meetings with Arsene Wenger will inevitably be accompanied by a re-run of their remarkably bitter exchanges during Mourinho’s first spell in the Premier League. But City, where Mourinho’s first-ever defeat as Chelsea manager was inflicted on 16 October, 2004, a day when the home crowd sang, “that coat’s from Matalan” at him, are new territory.

Would a third Premier League title with Chelsea be sweetest of all if they can do it this season? “There are no ‘ifs’. We win or we don't,” Mourinho said. “It's different. It can be better because I always say that the best trophy you have is the last [most recent] one. If we win something important with this group, it will be the best for many reasons.”