Chonburi were frustrated by lowly Sisaket on Wednesday as their goalless draw ensured they lost ground on their title rivals.
Masahiro Wada's side were the only team in the top eight not to pick up maximum points in midweek and it cost them two places as they slipped to fifth.
While the point does little good in helping Chonburi close the gap on the likes of Muang Thong United and BEC Tero Sasana, it could prove important for Sisaket who edged further away from the bottom five.
Ten-man Samut Songkram were beaten for a fifth game running - going down 3-1 to Chainat FC - while Air Force United were downed by Army United thanks to goals from Wellington Cirino Priori and Tanakorn Dangthong.
PTT Rayong came close to securing a point against 14th-placed Police United but were beaten by a late Pakorn Prempak strike six minutes from time.
Victory for Bangkok United would have moved them out of the relegation spots but they came out on the wrong end of a five-goal thriller against Suphanburi.
The hosts had the lead at the break in the capital thanks to Romain Gasmi's penalty but Jakkraphan Pornsai's equaliser coupled with a Robert Cullen brace did the damage - with Sompong Soleb's late goal proving a consolation.
Darko Tasevski was the hero for United's city rivals Bangkok Glass - scoring twice to condemn Songhkla United to defeat.
In the upper reaches of the table, Buriram United moved to eighth as goals from Kai Hirano and Javi Patino saw off Osotspa while TOT suffered a damaging 1-0 defeat to Chiangrai United - Keita Sugimoto scoring a minute from time.
Without a win in their previous four games, the last thing Singhtarua will have wanted was a visit from leaders Muang Thong United.
So it proved as Erik Paartalu, Datsakorn Thonglao, Teerasil Dangda and Milan Bubalo were all on the scoresheet in a 4-0 mauling as the three-time winners moved past the 30-goal mark after 14 games of the campaign.
Sho Shimoji's brace helped BEC Tero Sasana keep in touch with the leaders - with the weekend's fixtures offering Jose Alves' men a potentially golden opportunity as Muang Thong meet third-placed Army United.