The Rabbits showed hosts Samut Prakan City no mercy as they maintained their 19-point lead at the top of the table.
With only seven matches remaining this season, Pathum could wrap up the title at their home ground on Thursday when they host Sukhothai.
Diogo Luis Santo had a hat-trick, Victor Cardozo struck twice and Santiparb Channgom scored one goal for the Rabbits.
Meanwhile, Port ended their five-game winless run in the league, which included four losses, with a 3-1 home victory over bottom-placed Rayong that helped them reclaim a share of second spot last night.
Former champions Buriram United, who defeated Nakhon Ratchasima 3-0 in a northeastern derby on Saturday night, had taken sole possession of second spot, but Port’s victory last night helped them tie the Thunder Castle on 44 points.
Port went on the front foot from the word go and found themselves leading the visitors 1-0 in the sixth minute when Nelson Bonilla set up Siwakorn Jakkuprasart to score from close range.
Khlong Toey-based Port got their second in the 38th minute when Pakorn Prempak crossed the ball to Sergio Suarez to score with a header.
Rayong were able to reduce deficit by one early in the second half but Metee Sarakum’s strike was followed by a penalty for Port which was converted by Suarez to seal the fate of the match in the 83rd minute.
Struggling Chonburi also found their scoring boots again at their home ground and handed Suphanburi a 4-1 defeat.
Suphanburi had a quick goal through Rithiporn Warnchuen, but Chonburi then hit the target four times as Renato Kelic (10th minute), Kritsada Kaman (22nd), Panupong Polsa (47th) and Eliandro (80th) scored for the Sharks.
Also last night, fifth-placed True Bangkok United were 1-0 winners at Sukhothai thanks to an 18th minute strike from Vander Luis.