Resurgent Port made the most of their trip to relegation-threatened Suphanburi by recording a 3-1 victory that helped them close the gap on second-placed Chiang Rai United on Sunday night.
It also helped that the Beetles stumbled in their chase of the Thai League 1 title with a 1-1 home draw against Sukhothai late on Saturday night.
Buriram United, following their massive 6-0 victory over Ratchaburi on Saturday night, lead the standings with 47 points, followed by Chiang Rai United (44) and Port (43).
After going winless for six matches under former coach Jadet Meelarp, Port are enjoying a big change in fortunes under new boss Choketawee Promrut, winning four matches in a five-game unbeaten spree.
Port were put in front by Rolando Blackburn in the 29th minute and the visitors had a stroke of luck early in the second half when Suphanburi midfielder Thanasit Siripala misguided a header into his own goal.
Suphanburi reduced the deficit near the hour mark when Michael Seroshtan struck home, but Port continued to dominate and were rewarded with a third goal in the last minute through Nurul Sriyankem.
Meanwhile, SCG Muang Thong United wasted a two-goal lead to allow visiting PTT Rayong pull off a 2-2 draw.
Heberty Fernandes won a penalty and coolly converted it in the 28th minute, and Derley scored from close range nine minutes later. But Rayong hit back with two second-half goals from Dennis Murillo and Adriel Rodriguez.
Trat beat Chiangmai 3-1 and Chonburi edged Nakhon Ratchasima 2-1.