Lucas Costa scored the winning goal as Port defeated Muang Thong United 1-0 at their PAT Stadium in Thai League 1 on Friday night.
The Brazilian was left unmarked and headed home from a Kaka Mendez corner kick in the 80th minute of the match to seal all three points for the home side.
Port moved up to third place in the 16-team standings with 16 points from nine games. The Kirins remained in ninth place with 10 points.
“Today was a big match and it was an important game for both teams. We kept our concentration and controlled the game well today,” said Port coach Alexandre Gama.
“We knew that today Muang Thong would be defensive and play a counter-attacking game. It was difficult because they defended deep and waited to counter-attack. But I have to praise our players because they kept going for the goal. Today we got our three points and did not concede.”
On Sunday, leaders and defending champions Buriram United host Rayong at their Chang Arena.
In other games on Sunday, second-placed Bangkok United face struggling Lamphun Warriors at their True BG Stadium, fifth-placed BG Pathum United visit Sukhothai, while Uthai Thani play visiting Ratchaburi.
Meanwhile, the Football Association of Thailand (FAT) announced that a minute’s silence will be observed and digital tributes will be displayed at the stadiums before all domestic matches while players, officials and match referees will wear black armbands following the passing of Her Majesty Queen Sirikit, The Queen Mother on Friday night.