Cork City gained their first win of the season in the battle of the bottom two teams with a huge 6-0 win.
In a very open game, Cork City scored two in a four minute burst in the first half through Daryl Horgan and Davin O'Neill.
Forward Vinny Sullivan added another after 48 minutes after which Monaghan's Keith Quinn picked up a second yellow card for dissent.
Further goals from sub Tadgh Purcell and two further from O'Neill meant he completed a hat-trick and Monaghan's annihilation.
Before the game Monaghan United manager Roddy Collins admitted that he would be happy with a point. At half-time, he would have been delighted with parity.
By full-time, a draw was a distant memory and he would have settled for keeping the score down.
Instead his side lost the battle of the leagues two winless sides by a landslide. This may belatedly kick-start Cork City's season and do the opposite for Monaghan's.
Unlike earlier matches when Cork City were at home, in the lead and enjoying a numerical advantage, they made it count this time.
They stretched Monaghan at all opportunities and kept the ball moving. Unlike many games this season and last, they didn't sit back when they hit the lead.
Monaghan kept attacking too, to their eventual detriment. What was an open game in the first half, became far too open in the second half for Monaghan.
A four minute burst in the first half set the tone for the match. Both sides had had shots taken off the line before that, but it was City who made the breakthrough.
After 27 minutes, winger Daryl Horgan picked up the ball in midfield and attacked the retreating Monaghan defence at pace.
His central shot looked to be covered by 'keeper Chris Bennion until Shaun Maher deflected the ball past him.
Five minutes later Davin O'Neill scored from close range after the 'keeper dropped the ball from a free-kick. Monaghan never recovered.
The killer blows came just after half-time. First Vinny Sullivan chested in a goal from a whipped Gearoid Morrissey free on the left after 48 minutes.
By the time Monaghan kicked off again, they were down to ten men. Keith Quinn had been carded for an ugly foul on man of the match Daryl Horgan in the lead up to the goal and he picked up a second yellow for dissent.
Thereafter, Monaghan kept attacking and paid the price for it. O'Neill knocked in a fourth after 65 minutes via a sharp counter attack. Tadgh Purcell hit one in off the post from the edge of the box after 77 minutes.
Davin O'Neill completed his hat-trick after 86 minutes, stroking a penalty into the corner, after a foul on Shane Duggan.
It left a crowd of 2,431 delighted in Turner's Cross and Roddy Collins with a long unhappy journey back to Monaghan.
Cork City: Mark McNulty, Danny Murphy, Gavin Kavanagh (Ian Turner 70'), Gearóid Morrissey, Shane Duggan, Davin O'Neill, Vinny Sullivan (Tadgh Purcell '70), John Dunleavy, Dan Murray, Kalen Spillane, Daryl Horgan (Shane O'Connor '76).
Monaghan United: Chris Bennion, Jordan Keegan (Owen Humphrey 56'), Conor McMahon (Jason Marks '73), Conor Murphy, Keith Quinn, Darragh Reynor (Roddy Collins '73), Willo McDonagh, Danny McGuinness, Shaun Maher, Stephen Maher, Gareth O'Connor.
