Manchester City are not assured of winning this season's Premier League title despite having shown a more ruthless streak, according to former manager and player Peter Reid.
Victory over Manchester United saw the reigning champions return to the top of the table, re-establishing their two-point advantage over Liverpool.
Pep Guardiola's side have only dropped four points this term, remaining unbeaten after 12 games and have already netted 55 goals in all competitions.
But Reid says that despite City displaying little mercy this term, the likes of Liverpool, Tottenham and Chelsea remain contenders for the championship.
"I don't believe this season's title race is a foregone conclusion," he wrote in the Daily Mail.
"Guardiola won't either. Football has proven too many times that hiccups happen.
"Jurgen Klopp, Maurizio Sarri and Mauricio Pochettino are all fantastic coaches with excellent teams and resources to compete.
"You can bet Jose Mourinho, a serial winner in his career, won't be taking this lightly... whatever he says publicly.
"This City team are exceptional but it's not over yet."
First half goals from David Silva and Sergio Aguero had put the hosts on course for victory, before United threatened a comeback after Anthony Martial's penalty.
Not until substitute Ilkay Gundogan hammered home a late third did City secure the points.
Reid believes City have developed into a more pragmatic outfit which makes them a more dangerous proposition.
"It may seem ominous but the difference I've seen in Manchester City this season is that Pep Guardiola is more hard-bitten," he added.
"In previous years you could argue he let his purist principles get in the way.
"City had to play total football even if it came at a cost.
"Against Liverpool at Anfield, where they have struggled a few times, I saw Guardiola set up in a tactical manner which respected Liverpool's strengths on the break.
"Against Manchester United on Sunday with the score at 2-1, he brought off Sergio Aguero and added Ilkay Gundogan to gain extra control.
"Last season, that may not have been the case. but in both instances this time City benefited.
"There's an edge, perhaps a more ruthless nature about them. They absolutely hate being beaten."