Super-sub Rob Lehane struck the only goal of the game to leave the race for the title nicely poised with five matches remaining.
City boss John Caulfield was delighted with the three points – Cork have now beaten Limerick four times this season — and has vowed his side will slug it out with Dundalk until the final game of the season.
“There weren’t a lot of opportunities in the match, I said at half-time that we get a lot of late goals and one goal will probably win the match, he said.
“Rob came in, we’ve missed him for a long time. He got a fantastic strike to win it and it keeps us on the heels of Dundalk and probably close to Europe as well. We have a huge game on Friday against Sligo.
Shane Tracey had the ball in the net in the third minute, but Rory Gaffney, who was in the line of play, had come back from an offside position.
Cork had appeals for a penalty turned down in the 15th minute after Mark O’Sullivan and Stephen Folan became involved in a wrestling match inside the area – but the ref gave a free out.
Folan again denied O’Sullivan with a well-timed challenge minutes later, but then almost miscued Colin Healy’s shot from the rebound into his own net.
Limerick forced three corners in quick succession midway through the half, culminating in a long range effort from Kieran Djilali which was saved at the near post by Mark McNulty.
City almost went in front 18 minutes from the break, courtesy of a solo effort from Dennehy. The Cork midfielder went flying into the area past two defenders, but Ryan dived bravely at his feet.
The hosts responded via Gaffney. The Limerick striker was ploughing a lone furrow up front all evening, but he almost opening the scoring with a low 25-yard drive which was brilliantly saved by McNulty.
Dennehy should have put his side ahead shortly after the interval but, alone in the area, he volleyed straight at Ryan, who palmed the ball to safety.
McNulty dived at the feet of Darragh Rainsford with 18 minutes remaining, following great work from Djilali, but Cork had a glorious chance minutes later. Gearóid Morrissey broke free down the middle and played the ball through to O’Sullivan, but O’Sullivan hesitated before pulling the trigger and the chance was lost.
However, the Leesiders went in from 11 minutes from time. Morrissey played the ball in from the left and Lehane side-stepped a challenge before smacking a low drive into the far corner of the net.
McNulty saved from Rainsford in the closing minutes, but that was the nearest Limerick came to an equaliser on a night when Cork reminded Dundalk that they can’t afford any slips up going down the final stretch.
LIMERICK FC: Ryan, Nzuzi, Folan, Leahy, O’Connor, L J-Lynch, Agyemang Tracey (Mann 80), Djilali (Oji 80) Doherty inj (Rainsford 58) Gaffney
CORK CITY: McNulty, Dunleavy, Morrissey, Gaynor, Murray. Healy, Murray, McSweeney, Dennehy (O’Leary 85) Kearney (Lehane 60) O’Sullivan, O’Shea (Kavanagh 82)
Referee: D Twomey (Dublin).