Dundalk left it late to defeat Shelbourne, with Tiarnan Mulvenna's 87th-minute strike proving the difference after Brian Shortall was sent off for the visitors.
Dundalk almost went ahead in the first minute, but Kurtis Byrne could not properly connect when put through on goal by John Dillon. The duo teamed up once again a few minutes later, but once again Byrne's effort was a weak one. Shels forward Philip Hughes had a penalty shout turned down as the visitors began to come into the tie.
Keith Ward had the best chance of the first half, linking up with the impressive Richie Towell before putting a shot narrowly past the post. The hosts had another decent chance before the break, but Dillon's rising effort went just over Ger Hanley's crossbar.
Hanley almost allowed his side to go behind just after the interval, but Stephen O'Donnell's shot came back off the post after the goalkeeper failed to claim the ball when challenging Vinny Faherty. Hanley did well on the hour mark to keep out Faherty's header as Dundalk began to take hold of the tie.
Shels were reduced to 10 men with just 12 minutes remaining as Brian Shortall was dismissed for a dangerous challenge on Pat Hoban. This spurred Dundalk on further, and they finally got the goal they deserved when Tiarnan Mulvenna cooly struck the ball past Hanley with just three minutes left on the clock.
The late goal sees Dundalk keep up their good run, and stay in contention with the league leaders, with just two points now separating them and second-placed Derry City.