Cork Constitution turned the screw in the second half as they fought back from a seven-point half-time deficit to overcome Blackrock College.
All of Blackrock's good work in the opening 40 minutes at Stradbrook was cancelled out by the Leesiders' improved efforts after that.
Ireland underage international Brian O'Hara crossed for two tries for the visitors, who had a seven-point contribution from influential scrum half Gerry Hurley.
But it was Blackrock number 10 Darragh Fitzpatrick who took centre stage early on, his instinctive try and three penalties helping Eric Miller's men take a 14-7 advantage.
Still, 'Rock had only won one of their previous five league games and that lack of nous hurt them as Brian Walsh's charges applied the pressure.
They increased the intensity, particularly up front where Brian Hayes, Andrew Cudmore and Brendan Cuttriss were prominent throughout.
The reliable Hurley knocked over a difficult penalty and converted flanker O'Hara's second try as the lead changed hands at a crucial point of the game.
The visitors had tightened the reins on Blackrock considerably at this point and even though they did their best to force the proceedings late on, Cork Con held firm to take the verdict and move up to third in the Division 1A table.
Referee: Simon McDowell (IRFU)