Danny Invincible scored with a header 10 minutes from time as Army United ground out a 1-0 victory over relegation threatened Thai Port.
Bjorn Lindemann spurned a great chance for Army as he scooped over the bar from close in as the first half passed by in unspectacular fashion.
After the break, Army's most likely route to goal appeared to be from set pieces yet it was Kosin in the host's goal who had to make two blocks from Bawe and Thongchai as the game finally came to life in the last quarter.
Army, though, finally got the breakthrough when Tony Costa crossed from the left for Invincible to fire a header home.
The game turned ugly towards the end as a clash between Mario Silva and Danny Invincible produced a scuffle on the near touchline. There appeared to have been a couple of slaps thrown although the intervening match officials and coaching staff did just enough to stop a mass brawl erupting.
Defeat leaves Thai Port just two points above safety whilst Army, who remain unbeaten in seven league games, remain sixth but more notably move to within three points of second placed Buriram United.