Pablo Zabaleta believes Wayne Rooney's refusal to throw in the towel at the Etihad Stadium proves Man City are just as big a rival to Man United as Liverpool.
In the build-up to yesterday's game, Rooney claimed Liverpool remain United's greatest rivals despite City's present status as one of the Premier League's powerhouses.
The comments were interpreted as a put-down to City, who won their first title since 1968 when they pipped United with virtually the last kick of the 2011-12 campaign.
Yesterday's 4-1 win for City underlined what a threat they are.
But more than that, Zabaleta saw in Rooney's sheer determination where the Blues have risen to.
"I saw Rooney," said Zabaleta.
"He was one of Manchester United's main players and tried more than anyone else in their team.
"He said Liverpool is still the big game but when I saw him working so hard it probably proves this game is just as important to him and United as Liverpool."
City's biggest home win over United since 2004 could hardly have been more comprehensive.
In scoreline terms, the 6-1 triumph at Old Trafford two years ago may have been greater.
However, that match was tilted in City's favour by Jonny Evans' red card and also contained a bizarre period of injury-time in which the Blues scored three times.
There was nothing so freakish in evidence yesterday as Manuel Pellegrini's men simply outclassed their opponents - Rooney apart - in every area of the pitch.
And when Sergio Aguero and Samir Nasri scored in quick succession just after the interval, even Zabaleta wondered whether a repeat of that epic Old Trafford success was on the cards.
"When we scored the third goal, everybody thought that it could be another chance to do it," said Zabaleta.
"Just for a moment even I thought about the 6-1 game.
"But after we scored the fourth goal we lost a bit of intensity."
Nevertheless, it was a day to cherish, one of those rare occasions when everything seems to go right.
"When the game is like that, and you see the team playing like that against a team like Manchester United, you know it is special," said Zabaleta.
"The fans understand everything is great.
"We were fantastic and very solid at the back. We created lots of chances and they had only one or two shots on.
"That is hard to do against a team like United."
It also provides a significant lift to Manuel Pellegrini, whose side have struggled in the opening weeks, losing at newly promoted Cardiff and then being outplayed at Stoke last weekend.
"This result has helped the manager, his staff and all the new players," said Zabaleta.
"Winning like that gives you confidence.
"It should help the team to play much better collectively than we have done.
"If we carry on playing like that in such a big match, we have a lot of chance to fight for the title.
"But we have to be ready to play every game the same way. Sometimes we talk about mentality and focus on every game in the Premier League because we know how important it is.
"It is true the way we played in the last games was different so we must try to keep the same intensity as it was against United."