Port opened a two-point gap at the top of the Thai League 1 table with a 3-2 victory over visiting Lamphun Warriors on Sunday night.
Port struck in the 32nd minute when a feeble clearance let Kevin Deeromram score from close range.
Five minutes before half-time, Port were denied a goal as a VAR check ruled out an effort by Barros Tardeli.
Lamphun equalised through Taua Ferreira on 53 minutes but Port surged ahead again five minutes later when Hamilton Soares converted a penalty.
In the 64th minute, Bordin Phala made it 3-1 before the Warriors narrowed the margin after 75 minutes through Akrapong Poomviset.
In other games on Sunday night, hosts Police Tero edged Muang Thong United 2-1 and PT Prachuap suffered a 2-1 home defeat to Uthai Thani.
BG face tough test
BG Pathum United will be trying to seek their first point in Group I of the AFC Champions League when they host Japan's Kawasaki Frontale on Tuesday.
Having lost to South Korea's Ulsan Hyundai and Malaysia's Johor Darul Ta'zim, the Thais need a result to stay in contention for a place in the next round.
After two games, Kawasaki have six points while Johor and Ulsan each have three.
Pathum are expected to be led by playmaker Chanathip Songkrasin who will face his former club.
Ulsan are at home to Johor in the other Group I match on Tuesday.
