Varsity A came out with all guns blazing in the second spell to beat Southern 35-27 and book a spot in the Dunedin club rugby final next Saturday.
Southern looked to have the game in its grasp when it led 24-10 at halftime.
But the students were having none of it and attacked from all parts of the paddock in the second spell to score three more tries and 25 points.
The hero for the students was first five-eighth Stephen Fenemor, who kicked six goals and scored 15 of University A's points.
The ground was soaked and the ball wet in the second semi-final, which Taieri won 20-3 when it strangled last year's champions, Dunedin, out of the game.
New Otago captain Charlie O'Connell was the hero with his ability to break the advantage line with the ball in hand.
Flanker Hugh Blake had a strong defensive game for Dunedin
Taieri will meet University A in the final at the Forsyth Barr Stadium at 2.30 pm next Saturday.