Ratchaburi produced a magnificent comeback to overturn a 1-0 deficit, despite going down to 10 men midway through the second half.
Mario Durovski put Muang Thong in front after 42 minutes, before midfield counterpart Chutipol Thongtae was sent off for Ratchaburi.
But the visitors were undeterred by the numerical disadvantage and produced a dramatic late turnaround, Phuwadol Suwannachart scoring a last-gasp winner after Muang Thong midfielder Worakraj Thongkruea had put through his own net.
Three-time champions Muang Thong had led the way prior to that defeat, but have now been leapfrogged by the unbeaten pair of Ratchaburi and newly promoted Singhtarua, who went top with a 3-0 win over Samut Songkhram.
Leandro Oliveira gave Singhtarua the lead from the penalty spot, before goals from Kroekit Thaweekarn and Sarawut Khongchareon made sure of the points.
A double from striker Thanakorn Danthong moved Army United into fourth with a 2-1 success against winless Songkhla United, while defending champions Buriram United beat PTT Rayong 2-0.
Kai Hirano and Carmelo Gonzalez netted for Buriram, who claimed only their second victory of the campaign.
Chonburi overcame Bangkok Glass in a 3-2 thriller thanks to injury-time strikes from Chakrit Buathong and Thiago Cunha, and Chiangrai United won 2-0 at Suphanburi in a game that saw both sides reduced to 10 men.
Bireme Diouf was dismissed shortly after the hour mark for Suphanburi, before Renan Marques, who had earlier given Chiangrai the lead saw red for a second bookable offence late on.
Gorka Unda scored the only goal of the game in Sisaket's 1-0 triumph over Police United, and Osotspa drew 1-1 with TOT.
Air Force Central are still waiting for their first win after a goalless draw with BEC Tero Sasana, while Bangkok United’s clash with Chainat Hornbill ended in the same result.
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