Carr was dropped for Saturday night's showdown after five weeks of what coach Mark Williams described as patchy form.
On the weekend, Carr pulled on the Glenelg jumper for the first time in more than five years and Cornes said the 29-year-old had done enough to earn an AFL recall.
"Carry went back to Glenelg with a great attitude. He had about 36 possessions and was nearly best on ground. It shows the character of the guy and with Hamish Hartlett going down injured and probably missing this week, there's certainly a spot there for Josh," Cornes said on Tuesday.
"He's been on and off the bench for the first five rounds of the AFL season, so just to get that fitness and confidence back — I think he's done enough and he can certainly come back and add to our side."
Prized number-four NAB AFL Draft pick Hartlett is likely to miss Saturday night's clash with North Melbourne.
He injured his hamstring early in the win over Adelaide, but Cornes said the promising teenager could be fit to play as early as next week.
"Hamish has been fantastic," Cornes said.
"He's going to be a 10-year player and a star of the competition, so it's a bit disappointing (to have him out of the side), but the injury is very minor."
In the opening six rounds, Port Adelaide has already experienced the highest of highs, having beaten Hawthorn at the MCG, and the lowest of lows, after losing to St Kilda at home by 11 goals.
Cornes said it was important for the club to string two good games together with a win over the Roos.
"We've got a good opportunity to set up the year – we could be 5-2 if we have a win this week, so this week is as important, if not more important, than the showdown," he said.
"I think we had a great learning experience after the St Kilda game (in round five). We came back after beating Hawthorn and probably thought we were a bit ahead of what we were.
"But we won't know how much we've learned until we front up this week and bring the same attitude and intensity we brought Saturday night."
Port Adelaide has started to rectify a lop-sided win-loss record against North Melbourne and Cornes – the Power's resident statistician – said his side was keen to get another one up on the boys from Arden Street.
"We've got a pretty good rivalry against North. They always used to beat us in the early days and just recently we've started to square the ledger a little bit," Cornes said.
"I think the last six times we've played them, it's 3-3 and we don't play well at the [Docklands].
"I think in of our past seven games there, we've only won one. That's an area the group really needs to improve in because obviously some big games are played at the [Docklands]."
