Dean Shiels' extra-time winner eventually took Kilmarnock past local rivals Ayr United 1-0 in their Scottish Communities League Cup semi-final at Hampden.
The Clydesdale Bank Premier League side dominated throughout but were thwarted by brilliant Ayr keeper Kevin Cuthbert who made great saves in the second half from Gary Harkins, Shiels, Manuel Pascali and Garry Hay.
However, Cuthbert's stubborn resistance was broken in the 109th minute when Shiels, who had recovered from illness to play, drove low into the corner to set up a final appearance against either Celtic or Falkirk who play in the second semi-final at the national stadium on Sunday.
It was a deserved win for Kenny Shiels' side but they certainly made hard work of a game they should have won easily on the balance of possession and chances created. However, that will not bother the Killie fans who look forward to their first final appearance in the competition in five years.
In the 23rd minute Ayr captain John Robertson had to head clear a chip from Killie midfielder Hay from close to his own goal and that was the closest the first half came to a breakthrough for either side. Three minutes later Hay ended another spell of Rugby Park pressure with an effort from distance which Cuthbert clutched to his chest.
Ayr's first effort on goal came in the 33rd minute when Michael McGowan curled a free-kick from 25 yards over the Killie bar, before Shiels again drove wide at the other end.
Killie forced a corner within a minute of the restart after Ben Gordon ended a fine overlapping run into the box with his cut-back blocked but it came to nothing. Five minutes later on the other wing, James Dayton went past Ayr defender Eddie Malone and burrowed his way into the United box but could not pick out a team-mate and another opportunity was lost.
Ayr keeper Cuthbert then came into his own. In the 66th minute he parried Dayton's 25-yard drive to the feet of Harkins and stuck his leg out to deny the Killie striker's close-range strike which looked certain to give the Rugby Park side the breakthrough.
In the 79th minute Cuthbert stretched to tip Shiels' 30-yard drive over the bar and from the corner knocked Pascali's downward header past for another corner which Ayr survived. In the second minute of extra-time Killie substitute David Silva, on earlier for Dayton, screwed an angled drive wide of the far post.
In the 109th minute Shiels eventually got the breakthrough against a desperately unlucky Cuthbert. The Northern Irishman's first drive was parried by the former St Johnstone keeper, who then saved from Paul Heffernan but when the ball came out again Shiels rifled it low into the net.