David Connolly of Monaghan on the ball against Cavan
A stoppage-time goal by Michael Greaney swung this Ulster Hurling Championship match in Monaghan's favour.
It was a close encounter and the sides were locked on 11 points each when a sideline cut by Cavan's Eugene Hill went straight into the net.
Arthur Hughes hit back with a goal for Monaghan but Cavan went four points up through two gems from Kevin Downs.
Monaghan pulled two back through Brian McGuigan and Stephen Lambe and then Greaney landed a goal and a point.
Monaghan now face Donegal in the revamped championship.