Stephen O'Flynn's injury-time equaliser forced FAI Ford Cup holders Sporting Fingal into a replay after a 2-2 draw at Morton Stadium.
The goal capped a remarkable comeback for Pat Scully's Limerick, who fought back from being 2-0 down at the break and played the last 20 minutes with 10 men.
The small crowd had barely settled in their seats at Morton Stadium before the holders went in front. Ronan Finn was at the heart of a slick passing move that saw Gary O'Neill thread the ball through for the midfielder, who hit the net.
Conan Byrne doubled the lead, meeting Shaun Williams' cross-field ball with an inch-perfect volley to beat Davy Ryan. But Limerick came out fighting after the break and Pat Purcell pulled a goal back within five minutes of the restart as Shane Treacy's corner found the centre-half, and he headed in off the post.
The goal seemed to buoy the visitors and, although Ollie Cahill went close for Sporting, Limerick grabbed an equaliser when Fingal failed to deal with another set-piece and the ball fell to O'Flynn who bundled home to force a replay at Jackman Park on Monday night.