SCG Muang Thong United striker Siroch Chatthong missed a sudden-death penalty to hand Chiang Rai United a place in the FA Cup final, as the Kirins bowed out following a 6-5 shoot-out defeat on Wednesday night.
Charyl Chappuis and Heberty Fernandes ensured a 2-2 draw for Muang Thong with late strikes after Chiang Rai had gained a two-goal advantage through second-half goals from Suriya Singmui and Sivakorn Tietrakul.
Both sides failed to break the deadlock in the extra-time and the semi-final was decided on penalties.
After the first set of five penalties each, both Chiang Rai and Muang Thong found themselves tied 5-5 before Thailand international Siroch's misdirected shot off the spot was saved by goalkeeper Chatchai Butprom.
Chaiyawat Buran then planted the ball into the net to settle the sudden-death shoot-out and help Chiang Rai set up a Nov 25 title showdown with Bangkok United at Supachalasai Stadium. Bangkok United defeated JL Chiang Mai 3-0 in the first semi-final on Wednesday night.
Chiang Rai United coach Alexandre Gama called the result a "historic achievement", referring to the fact that it is the first time that the northern side has qualified for the FA Cup final.
"It was a quality match. We recovered well after a lacklustre start and were lucky to get two goals early in the second half," said Gama.
"Our goalkeeper Chatchai Butprom did a great job today despite suffering an injury during the match.
"The focus is now on the League Cup semi-final with Ratchaburi [tomorrow]. We might have to use some of our reserve players against Ratchaburi as tonight's game is likely to take its toll on some of our regular starters."
Muang Thong coach Totchtawan Sripan said: "Anything we say or do now won't change the result, so congratulations to Chiang Rai. I think it was an exciting game and both sides played very well.
"We missed some shots in the penalty shoot-out but I don't want to blame the players.
"We only have one trophy left to battle for, so it is time to forget about everything else and concentrate on [tomorrow's] FA Cup semi-final against Police Tero."
Buriram lead the Thai League 1 table with 77 points from 31 matches and need only a draw in their three remaining games to wrest the title from the Kirins.
