After last week's 3-0 loss at Rayong FC, Bangkok's promotion fate was out of their own hands and there was a sombre end of season feel to the contest as the match kicked off.
It was an even start to the game although it was Krabi who had the early chances with Anuwit and Somkid coming close.
The hosts first real effort came midway through the half when Tawin's drilled left foot shot across goal forced Anusorn to block with his foot.
The same duo were involved three minutes later when the goalkeeper rather recklessly brought down the Bangkok number 22 leaving the referee with the simple decision of awarding a penalty.
Lee Tuck took his trademark stuttered run up for the spot kick but Anusorn dived the right way to block his shot. However, Meedech was the swiftest to react and he knocked in the rebound to give the hosts the lead.
After the interval, Bangkok were applying most of the pressure while the team from the south were looking dangerous on the break.
Tawin's header from a long throw went just over the bar and an Olof Watson shot hit the side netting as the hosts pressed. At the other end, John Mary couldn't connect properly as his shot 18 yards was saved by Worawut and Anuwit blazed over following a quick break.
The Bulligans thought they'd taken the lead shortly after Sam Danquah's arrival but his teasing cross was knocked tantalisingly back across the goal by Watson with the Krabi keeper stood rooted to the spot.
With time running out, Bangkok FC were awarded a debatable penalty. Whether or not Adisak clipped Jutarong is open to discussion, but the reaction of the Krabi players was rather childish. In the rugby scrum that swarmed the man in the middle afterwards, it appeared a slap was aimed at his head and Onuora was shown a red card. After about 15 minutes of heated argument on the touchline, the red card was given to Thaweephong after he appeared to own up. Lee Tuck could finally take his second spot kick off the afternoon and this time the Englishman made no mistake as he sent Anusorn the wrong way to make it 2-1.
Moments later, Bangkok should have had a third penalty but the referee decided to hedge his bets and awarded a free kick on the edge of the box instead. Tuck then gently rolled the ball to Watson and the Swede rifled home into the bottom corner to secure the 3-1 win.
There was double joy at the final whistle for the Bang Mot side when the news filtered through that Nakhon Ratchasima had beaten PTT Rayong. Next week PTT Rayong host Bangkok FC and a win for the Iron Bulls would send them into the TPL.