Trailing at the break to Grant Holt's 28th minute penalty, Posh were transformed from the re-start with 19-year-old Crow virtually unstoppable. First, the former Norwich City youngster levelled the scores on 55 minutes, stooping low for a header that made the most of a far from easy chance created by Dean Holden's cross to the far post.
Crow put the icing on the Posh cake and ensured only their second league home win of the season with a quarter of an hour left. He picked up the ball yards inside his own half and stormed towards Matthew Gilks' goal before burying a fierce low left-footed shot into the back of the net from the edge of the box.
In between Crow's goals, which brought his tally to four in three games, battling Posh defender Sagi Burton redeemed himself after returning from treatment to climb all over Holt and give away the first half penalty that set-up the Rochdale top scorer to hammer in his 12th of the season.
When Gareth Griffiths clipped the heels of Lee Thorpe to give Posh the chance to edge in front on 68 minutes, there was an amazing squabble between Crow, Burton and defender Mark Arber over who should take the spot-kick.
Eventually Burton received the nod from the less than happy manager Mark Wright on the touch line and he gleefully swept the ball low past the highly-rated Gilks.
Second in the table Rochdale, bidding to extend a four-match winning run, had the edge in the first half possession, but created few clear cut chances for Holt or his attack partner Rickie Lambert.
Apart from an early 35-yard shot from Posh loanee Thorpe that flashed a foot over the bar, it was the same story at the other end with Griffiths and Jon Boardman dominant in defence for Rochdale.