Roque Santa Cruz headed his first goal for Manchester City as Mark Hughes's side thrashed Scunthorpe to reach the Carling Cup quarter-finals.
Stephen Ireland gave City the lead with a curling shot before Jonathan Forte slotted in an equaliser for the Iron.
Santa Cruz converted Pablo Zabaleta's cross before Joleon Lescott headed home a Shaun Wright-Phillips corner.
Carlos Tevez prodded in from a Vladimir Weiss pass and Michael Johnson sealed a resounding win with a 25-yard drive.
City's victory ended a run of three straight draws on a night when Hughes was able to show off some of the impressive resources at his disposal.
Santa Cruz lasted the full 90 minutes on his first start since his £17.5 million move from Blackburn, while Johnson and Benjani were given useful run-outs following long-term injury layoffs.
Another player who has been short of first-team action this term, teenager Vladimir Weiss, could have scored a hat-trick in an impressive late cameo.
City wasted little time in asserting their authority over the Championship side.
With just three minutes on the clock, Wright-Phillips found Ireland and the midfielder was allowed to cruise to the edge of the box before calmly guiding the ball past Joe Murphy.
Wright-Phillips missed two chances to extend City's lead before Scunthorpe levelled things with an well-worked goal.
Nigel de Jong gave the ball away in midfield, and it was swept out to Marcus Williams on the left. His clever pass left Forte with a simple close-range finish.
606: DEBATE" As long as we are drawn at home we have a very good chance of getting through to the semis "
Nigel Adkins's side carried the fight to City during an impressive spell and could have gone ahead when Paul Hayes forced a smart save from Shay Given.
But City took the lead before the break when Zabaleta sprinted down the left and crossed to the far post for Santa Cruz, who planted a header across Murphy into the far corner.
Lescott gave City breathing space with his second goal in as many games before Weiss was sent on for his full debut in place of Ireland.
The 19-year-old was immediately into the thick of the action, teeing up Tevez for his fourth goal of the season.
Moments later, the young Slovakian collected the ball on the half-way line and beat three players before scuffing his shot.
City were rampant and substitute Johnson sealed an emphatic win with a rising strike into the top scorner.
Tevez received a standing ovation as he was replaced by Benjani, who was making only his third appearance of 2009 following a string of injuries.
Manchester City boss Mark Hughes:
"There were lots of positives to come out of the game when we played with the necessary intensity and tempo that made it difficult for Scunthorpe.
"We put on plenty of pressure and in the end they were not able to cope with it and we ran out comfortable winners.
"We wanted to finish the tie off and not repeat the draw against Fulham."
Scunthorpe manager Nigel Adkins:
"City have made it clear they want to win this tournament by the strength of the side they put out.
"If they had turned out a weakened side they could have come unstuck. We played well and created a lot of chances.
"But the quality of City shone through in the second half, the workrate was phenomenal and a lesson to our lads."