Limerick 1-1 Derry City
A 93rd minute equaliser from substitute Chiedozie Ogbene denied Derry City all three points, at Markets Field.
Centre-back Aaron Barry thought he had won the encounter for the Candystripes, but youngster Ogbene fired home with virtually the last kick of the game.
Derry made one change to their side which drew with Galway United on Monday night, with Nicky Low coming in for Ben Doherty, who dropped to the bench.
City also changed their formation going with Conor McDermott, Aaron Barry and Dean Jarvis slotting into a back three.
The home side started on the front foot but Robbie Williams' long range strike on two minutes was easily gathered by City keeper Gerard Doherty.
Minutes later Aaron McEneff saw his stinging drive, which had Limerick keeper Brendan Clarke scrambling, flash just wide.
Doherty had to make a super double save on 18 minutes, firstly with his right boot he kept out Dean Clarke's close range shot, then at full stretch he tipped over Shane Duggan's follow-up 20 yarder.
Just before the half-hour mark McEneff went close again with another pile driver, but Clarke kept the shot out and also did well to push the loose ball away from the in-rushing Nathan Boyle.
The first effort after the break came on 61 minutes but Tosi's left footed strike from the edge of the box failed to trouble Doherty.
City made a double change soon after with Mark Timlin and Mikhail Kennedy coming on for Joshua Daniels and Boyle, as they pushed forward for that all important opening goal.
The break through did come on 79 minutes as McEneff's left wing corner was fizzed into the near post and Barry made no mistake rising high to head home past Clarke from six yards.
Limerick made a double change themselves on 81 minutes with Bastien Hèry and John O'Flynn replacing Chris Mulhall and Paul O'Conor and they levelled things in stoppage time.
Centre-back Williams broke inside the City penalty area and his ball across the six yard box fell to substitute Ogbene, who's miss hit shot flew off the wet surface and high into the net, to spark wild celebrations amongst the home supporters.
Limerick: Clarke, Kelly, Whitehead, Williams, Robson; Duggan, O'Connor (Hèry 81); Mulhall (O'Flynn 81), Lynch, Clarke; Tosi (Ogbene 61).
Derry City: Doherty, McDermott, Barry, Jarvis; Daniels (Timlin 67), Low, McEneff, Monaghan, Curtis; McNamee, Boyle (Kennedy 67).
Referee: Mr Sean Grant (Wexford).