Young Munster fell to their third successive AIB League defeat as
Dungannon came from behind at Tom Clifford Park.
Two tries from winger Chris Cochrane got Dungannon into a winning position and John McGuckin's touchline conversion of the second touchdown proved crucial.
That kick put 'Gannon 17-16 ahead but there was further drama when Young Munster's Matthew Costello missed an injury-time penalty.
Three penalties from Costello had the Cookies 9-7 ahead at half-time but despite a Gareth Payne try, they ran out of steam.
