An Olof Watson second half double from the penalty spot helped Thai Port come from behind to beat BBCU 3-2.
There were a glut of goals shortly before half time as BBCU took the lead twice within the space of three minutes.
Moussa Sylla burst through the home side's rearguard on 42 minutes to set up Salahudin to score. The BBCU midfielder's boot seemed to connect simultaneously with a Thai Port defender's as the ball spun into the base of the net.
Within two minutes, the hosts levelled when Alex Ruella got to the front post to knock a header over Pornchai from Ponpipat's free kick.
However, parity was shortly lived as Juninho's pinpoint low shot crept into the bottom left hand corner to give the Big Bang a 2-1 lead at the interval.
The game was won in six second half minutes when Olof Watson converted two penalties. The first was awarded on 58 minutes as debutant, Ri Myong Jun, was blocked in the box. The Swede duly converted to level the contest.
Six minutes later, Sarawut was tripped and the referee pointed to the spot for the second time. Despite intimidation, Watson held his nerve to coolly slot the ball into the same side of the goal.
The BBCU players and staff were clearly vexed with the penalty decisions and surrounded the match officials at full time. The first one certainly looked like a penalty but for the second, I'd have to see it again before making a firm judgement.
On the whole, I thought the Klong Toei side deserved the victory. New boy, Ri Myong Jun gave the home side that extra bit of cutting edge up front even though there seemed to be a lack of communication at times with team mates. BBCU's Juninho had lively bursts and if he can find more consistency over 90 minutes, then he might provide the spark to keep BBCU in the TPL.
The victory lifted Thai port onto 22 points while BBCU's 19 points meant they slipped back into the relegation places.
EDIT: Having seen the replays of the 2 Thai Port penalty decisions on TV, I must confess that the second one was more convincing than the first one. Apologies!!