Sisaket goalkeeper Lucas Echenique scored a last-minute equaliser to stop Muang Thong United going clear at the Thai Premier League summit.
BEC Tero Sasana's 1-1 home draw with Bangkok Glass opened the door for Muang Thong to put open the gap at the top of the division to two points.
And, after Todsapol Lated had opened the scoring for the visitors at Sisaket, Jakkraphong Somboon's dismissal 16 minutes from time looked to have put the game to bed.
However, keeper Echenique popped up at the death to head home and salvage a 1-1 draw for struggling Sisaket.
Tero also squandered the lead in their clash on Saturday, with Sho Shimoji cancelling out Chatree Chimtalay's earlier effort.
Another draw saw Suphanburi miss out on the chance to close in on second, as they were held 1-1 by TOT, while Buriram United and Chonburi remain locked on 30 points in joint fourth after a 3-0 win over Chainat Hornbill and a 2-0 defeat to Bangkok United respectively.
At the other end of the table, Samut Songkhram climbed off the bottom with a 2-1 win at Police United, while Air Force Central - now at the foot - picked up a point with a goalless draw against Osotspa Saraburi.
Ratchaburi came from behind to beat a gutsy PTT Rayong 3-2, and Songkhla United's 2-1 win over Chiangrai United was their first victory in six league matches.
Elsewhere, Singhtarua triumphed 1-0 over Army United.