Down's John Clarke (left) is challenged by Barry Watters

Down led 0-4 to 0-1 early on but Cavan were level (0-9 to 0-9) by the break.

Barry Watters' goal put Cavan three up but they had Mark McKeever sent off and Down got quickly on terms only for them to have sub Colm Murney dismissed.

Danny Hughes' goal helped Down move three ahead but John McCutcheon's goal levelled late on before he was sent off and Hughes then struck the winner.

The Mourne County will face either Fermanagh or Derry in Saturday's final.

Derry take on the Erne County in Wednesday's second semi-final at Omagh (2000 GMT).

Kevin McKernan (two), John Fegan and Cathal Magee were on target for Down early on as they forged a 0-4 to 0-1 lead.

However, Michael Brides, Eddie Reilly and Gerard Pierson hit the next three scores as Cavan levelled.

Down did move two ahead again in the second quarter but two Finbarr O'Reilly frees before the break brought the sides level.

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Cavan looked to have struck a crucial blow when Watters slammed in his team's first goal six minutes into the second half.

However, almost immediately Cavan midfielder Mark McKeever received a straight red card after an off-the-ball incident and Down used their man advantage to reply with three quick scores to level.

Down sub Colm Murney was sent off after getting his second yellow card on 55 minutes.

Finbarr O'Reilly's point edged Cavan ahead again inside the final 10 minutes but Danny Hughes' 65th-minute goal put Down 1-14 to 1-12 ahead.

Cathal Magee's third point extended Down's lead to three but John McCutcheon then levelled for Cavan when he scrambled in his team's second goal.

McCutcheon's goal was his final involvement in the game as he received his second caution in the dying seconds of the contest to leave Cavan with only 13 players.

Hughes supplied the winner to put Down in the final.

John Fegan finished with five points for Down while Hughes contributed 1-2.