Ronan O'Gara displayed nerves of steel to land a last-minute penalty and seal a 24-23 win for Munster over Leinster - their first win over their fierce rivals in six attempts.
Man-of-the-match O'Gara kicked seven penalties from eight shots in a fascinating duel with his Ireland colleague Jonathan Sexton, who finished with six penalties to his name.
The Thomond Park victory was soured by a worrying ankle injury for Munster captain Paul O'Connell, but it could be hugely significant in securing a home Magners League semi-final for Tony McGahan's men.
They are 12 points clear of the chasing pack at the top of the table with just three rounds remaining.
Shane Horgan crowned his 200th appearance for Leinster with the only try of a furiously competitive first half.
Horgan's 21st-minute score was supplemented by five well-struck penalties from Sexton, giving Leinster a healthy 20-9 half-time lead.
O'Gara had kicked three penalties for the home side, but Munster produced a sizzling second half display as their tireless forwards took the game to the visitors to allow the fly-half and Paul Warwick to boot them to victory.