A year later than expected, Manchester United boss Jose Mourinho and Manchester City manager Pep Guardiola appear set for a season-long fight for the Premier League title.
Having overseen successful close-season spending sprees after lacklustre first seasons in charge at Old Trafford and Eastlands, Mourinho and Guardiola have put United and City in pole position among the early pace-setters.
After five matches, Mourinho and Guardiola have led their teams to identical records, four wins, one draw, sixteen goals scored, two conceded, and only alphabetical order is keeping leaders City above second-placed United.
There is little love lost between old rivals Mourinho and Guardiola and their close proximity in Manchester should make the title race an explosive affair.
Here AFP Sport looks at the key areas that transformed United and City:
Lukaku power play
Aware his most successful teams have always been built around a battering ram capable of combining power and poise at the focal point of his attack, Mourinho is reaping the rewards of splashing out £75 million ($101 million, 84 million euros) on Everton striker Romelu Lukaku.
At Chelsea, it was Didier Drogba and then Diego Costa who fuelled Mourinho's title-winning teams, while at Inter Milan he used Diego Milito to bully defenders into submission.
Lukaku, prolific but sometimes lacking desire at Everton, is following in those footsteps, scoring seven goals in seven appearances for United to transform an attack that was often held in check too easily last term.
"If you play for a big club, then you have to act like a big player and perform, week in, week out, Lukaku said of his United excellence.
City make case for defence
When Guardiola splurged £130 million on three full-backs over the summer, some critics suggested the Spaniard would have been better off using the money to strengthen other areas.
But Guardiola was convinced the additions of Kyle Walker, Benjamin Mendy and Danilo, from Tottenham, Monaco and Real Madrid respectively, were essential for his purist principles to be successful in England.
Guardiola loves to retain possession as his teams build from the back, while putting stress on opponents by using over-lapping full-backs to outnumber them in the final third.
Walker, Mendy and Danilo have allowed City to do exactly that, with Liverpool, Feyenoord and Watford crushed by a combined score of 15-0 in their last three games.
"They are having a big impact. We create spaces in behind and you need players in those positions," Guardiola said.
"Without these signings it would have been more complicated."
Matic brings stability
Asked how he felt about Chelsea sanctioning Nemanja Matic's £40 million move to United, Blues boss Antonio Conte gave a terse reply - "You should ask the club" - that left no doubt about his frustration at losing the Serbia midfielder.
Conte's loss has been Mourinho's gain as Matic's astute reading of the game and effective passing have provided the foundation for United's more creative talents to thrive.
Matic's presence in the midfield holding role had freed up Paul Pogba to take on the more attacking duties that suit his off-the-cuff style.
While Pogba will be sidelined with a hamstring injury for several weeks, Mourinho has no doubts United remain in good hands with Matic directing traffic.
Aguero rises to Jesus challenge
Just nine months ago, Sergio Aguero appeared in danger of being the odd man out in Guardiola's forward line following the arrival of Brazilian sensation Gabriel Jesus, but the Argentine has made himself indispensible with a blistering start to the season.
Despite Aguero's impressive track record at City, it was the more mobile Jesus who fitted the bill as the prototypical Guardiola forward and the pair played together only three times last season as the youngster took centre stage until suffering a foot injury.
However, Guardiola has unleashed the pair to devastating effect this season, with Aguero scoring six goals in six appearances, while Jesus has netted five times in six games.
Guardiola was especially delighted Aguero showed his creative side by laying on a goal for Jesus at Watford last weekend.
"He's a guy I encourage to play, not just to score goals," Guardiola said.