The home side had the better of the first half against the Dubliners, without a win in four games now, and almost went into the lead from an early Alan Kirby header.
Byrne was introduced on 22 minutes and he picked up a through ball from left winger Sean Prunty with five minutes remaining in the half. The 31-year-old former Irish youth international scuffed his edge of the penalty area effort skywards, but with Pat’s goalkeeper Chris Adamson back-pedalling, the ball incredibly dipped under the crossbar and over the despairing dive of the red-faced Adamson for the lead goal.
Pat’s best chance of the opening period fell to defender Barry Prenderville who latched onto the rebound of Keith Foy’s 20-yard shot, but Longford’s Stephen O’Brien got down well to save with his legs from close range.
Longford completed their third win over Pat’s in recent times, including their Cup final success and October’s 2-0 win at Flancare Park, with an injury time strike from Byrne once again, as strike partner Eric Lavine teed him up for his second of the night. The win effectively seals Longford’s Premier Division status for another yet, whilst Pat’s whose best efforts were through Welsh striker Tony Bird who twice grazed the Longford uprights, are out of European contention with Cork defeating Derry.