David Rochela's 86th-minute strike looked to have given the champions all three points, only for Brazilian striker Aron to level two minutes from time to ensure a share of the spoils for the visitors.
Second-placed Chonburi took full advantage of the league leaders' slip-up, cutting the gap at the top to two points with a 2-1 win over Sisaket thanks to goals from Krirkit Thaweekarn and Boworn Tapla.
Muang Thong United are six points behind in third with four games remaining after they kept their title hopes very much alive by beating Singhtarua 3-1.
However, BEC Tero Sasana's chances were dealt a huge blow by Ratchaburi, who sealed a 2-1 away win to leave the hosts eight points behind Buriram with efforts from Brazilian duo Douglas and Heberty, who further cemented his position as the league's top scorer with his 22nd goal of the season.
At the other end of the table PTT Rayong continued their recent resurgence by overcoming fellow strugglers Police United 3-1 to claim their fifth win seven matches, a result that moves them two adrift of safety after TOT drew 1-1 with Chiangrai United.
Muzafer Ejupi scored a second-half winner as Songkhla United kept their hopes of survival intact with a 3-2 away success at Bangkok Glass, but Air Force Central could be relegated on Wednesday following a 1-1 draw with Army United.
Elsewhere, Suphanburi beat Bangkok United 3-2, and Chainat Hornbill won 3-0 at already relegated Samut Songkhram.
