Rooney became only the fourth player in United history to reach 200 goals for the club when he scored twice in last night's 4-2 Champions League win over Bayer Leverkusen.
Manager David Moyes has already set Rooney the target of netting the additional 49 goals needed to join Sir Bobby Charlton at the top of the club's scoring charts.
It is not a milestone the 27-year-old can achieve this season.
However, in his present form, Carrick knows Rooney can cause some serious damage.
"It was as good as I've seen him for a while," said the England midfielder.
"He looked sharp and he looked hungry.
"His movement and touch was all there and he showed exactly what a player he is.
"It's great to have him in that kind of form."
There was never any real doubt once United dug their heels in over the prospect of Rooney joining Chelsea this summer that he would still try to perform at his best for his current employers.
But whilst there has been talk of a new contract for the former Everton player, who now has less than two years remaining on his present deal, the situation is anything but straightforward.
Rooney's reaction to being asked about his future on live TV immediately after last night's game was to dismiss the question rather forcibly.
As was the situation throughout the summer, it is Rooney's refusal to address the matter, or confirm his willingness to remain at Old Trafford, that fuels even more speculation.
His contract has to be addressed at some point too, and only then will there be any clue as to his real long-term thinking.
For now though, manager Moyes is just glad to have him around.
"I introduced him into the team at Everton, so I knew exactly what we were dealing with as a player," he said.
"To surpass Sir Bobby would be something because everyone respects him."
Between them, Rooney and Robin van Persie have now scored nine goals this season, a figure United will hope rises at Manchester City on Sunday.
"It is a bit of a dying thing now to see two forwards playing together," said Moyes.
"But the two of them are capable of scoring all kinds of goals and hopefully we are able to use it."
What is inarguable is that Rooney was a clear man of the match in United's best all-round performance of the season.
New-boy Marouane Fellaini impressed in the tidy manner of his work, with Carrick confirming his midfield partner is a valuable addition to the United squad.
"It was good to play with him," said Carrick.
"He is a real presence in there. He is such a dominant player and gives us something that we haven't had.
"You want options in the squad. There's no point in having similar players."
For all that, it is difficult to see Moyes' starting line-up changing too much for Sunday's Premier League trip to Manchester City.
Although it is 2010 since Nemanja Vidic and Rio Ferdinand last played together over three games in one week, with Phil Jones still not recovered from an ankle injury and neither Chris Smalling nor Jonny Evans featuring at all in a central position this season, it is impossible to envisage the veteran pair being split up.
Similarly, Van Persie and Rooney are automatic starters, as Carrick and Fellaini appear to be so the only question seems to revolve around the potential for Ryan Giggs replacing Shinji Kagawa as Danny Welbeck is not due to test the knee injury he suffered in training until tomorrow.
After a tricky start to the campaign, a repeat of last season's win at the Etihad Stadium would take United on to 10 points from those tough opening five matches, a more than acceptable return.
The bonus is United head across town on the same number of points as their rivals, who have also taken some time adjusting to their new manager.
"We've had a stop-start beginning to the season and people have been asking questions as normal," said Carrick.
"But the games against City are the ones you want to be involved in.
"It will be very intense and the atmosphere will be great.
"But we also know these big games can be won and lost on the finest of margins as we saw last year when a deflected free-kick won it for us.
"Hopefully it will be the same outcome this year."