Dublin football manager Dessie Farrell says their relegation from Division 1 gives his side food for thought going forward.
A last minute Jack McCarron free gave Monaghan a 3-13 to 1-18 win over the Dubs in Clones.
The recent six in a row All Ireland champions will play in the second tier for the first time since 2008.
Elsewhere Kildare will join the Dubs in Division 2 next season after suffering a 2-20 to 18 point loss to Mayo this afternoon.
That win for James Horan's men puts them into the league final against Kerry.
And it finished Donegal 1-14 Armagh 1-13.
Meanwhile Roscommon and Galway will be promoted from Division 2.
The Rossies beat their Connacht neighbours by 1-20 to 1-15.
Offaly will play Division 3 football next season after being pipped by Cork this afternoon, 1-21 to 1-20.
Down have also been relegated as they were beaten by Clare 2-14 to 1-9
Elsewhere it finished Meath 2-11 Derry 1-16
In Division 3, Limerick and Louth have been promoted after wins over Fermanagh and Wicklow respectively.
The Garden County are relegated to Division 4 alongside Laois who were beaten 2-17 to 1-13 by Longford.
