Jonjo Shelvey's stunning strike came seconds before the visitors had Stephen Sama dismissed but the Reds did not draw level until the 81st minute when Jon Flanagan put through his own net. The result means this match will be replayed in the semi-finals of the Barclays-sponsored competition with United enjoying home advantage.
The game between two of football's biggest foes got off to an explosive start with England international Shelvey slamming a 25-yard piledriver high into Ben Amos' net following a pass by Suso.
The Reds' response was swift as Adnan Januzaj released Ryan Tunnicliffe for a trademark burst forward. Sama resorted to committing a blatant professional foul on the marauding midfielder and was sent off, as he was in the corresponding fixture at St Helens.
Yet, as occurred in the goalless home draw with Wolves, having an extra man advantage from the early stages did not appear to be of any huge benefit to Warren Joyce's well-drilled side. Lacking an out-and-out striker, there was no real punch as the Merseysiders comfortably held their lead until the interval.
Januzaj found Tyler Blackett on the overlap but his cross bobbled towards Jesse Lingard, who had to readjust before seeing his shot blocked by Andre Wisdom. Another run by Lingard was ended with some calm defending by Wisdom while Amos had to be alert to push out a Suso cross during a rare breakaway.
Shelvey was fortunate to escape a second yellow card after chopping down Januzaj in full flow but United needed to improve after the break. Indeed, the hosts completely dominated the second