Port took possession of second spot in Thai League 1 with a convincing 2-0 away victory at Chonburi on Saturday night.
The result also helped Port narrow the gap at the top to seven points with a game in hand.
BG Pathum United, promoted to the top flight at the start of the season, are the runaway leaders with 35 points following their 2-0 win at Nakhon Ratchasima on Friday night.
Nelson Bonilla scored the first goal for Port a minute before the break with a left-footed angular shot as Chonburi goalkeeper Sinthaweechai Hathairattanakool was blinded by a bunch of teammates.
A counter-attack during the final minute of injury time gave Port their second goal of the night with Adisak Kraisorn adding to the visitors' tally.
Ratchaburi moved ahead of defending champions Chiang Rai on goal difference after claiming a 2-1 win at Suphanburi.
Also last night, bottom-placed Rayong pulled off a major upset, defeating fifth-ranked Sukhothai 2-1 at home. It's Rayong's only second win in 13 games of the season so far.
Bill boosts Beetles
Brazilian striker Bill Rosimar secured Chiang Rai United's first ever AFC Champions League win as the Beetles recorded a stunning 2-1 upset over FC Seoul in Doha on Friday night.
The victory kept Chiang Rai's hopes of making it to the knockout stages of the tournament alive.
It also helped the defending Thai League 1 champions gain a revenge for a 5-0 hammering at the hands of their South Korean opponents three days earlier.
Bill dealt the first blow to FC Seoul late in the first half before poking home the winner in the 89th minute.
The result has thrown Group E wide open with FC Seoul (six points), Melbourne Victory (three) and Chiang Rai United (three) all staying in contention for a second round berth.
Beijing lead the pool with 12 points from four games.
Chiang Rai will face Melbourne Victory tomorrow, when Seoul meet unbeaten group leaders Beijing.