Lansdowne 20 Dublin University 20
Division One bottom side Lansdowne allowed Dublin University in for two converted tries in the second half at headquarters as the students came from behind to steal a 20-20 draw.
The result - incredibly Trinity's fifth draw of a 13-game season - means Lansdowne are the top flight club who must face UCC - Division Two's third-ranked side - a relegation-promotion play-off in the coming weeks.
The afternoon had started well for Andy Doyle's home side as Leinster flanker Niall Ronan grabbed a 20th-minute try for a 8-3 lead.
Trinity's Simon Mitchell and Lansdowne fly-half Andy Tallon had earlier swapped penalties.
On 27 minutes, Lansdowne nudged further in front thanks to the classiest of their backs, Fiachra Baynes. His converted scored pushed Doyle's men 15-3 in front.
Six minutes later, Mitchell reduced arrears with his second penalty but a 38th-minute Tallon try - with Trinity skipper Martin Garvey in the sin-bin - gave the home side a 20-6 interval advantage.
Two tries in the space of 14 second half minutes cruelly undid all that good work though. Hugh Hogan bulldozed his way over on 56 minutes for the students.
The Barry Kinsella crossed the whitewash on 70 minutes - with Lansdowne prop Enda Bohan yellow carded - and Mitchell showing pin-point accuracy with the conversion to secure Trinity just their second ever season in the top flight.