Buriram United now need just one point from their last four games to retain the Thai League 1 title.
The Thunder Castle beat Lampang 2-0 while second-placed Bangkok United were stunned 2-1 by Lamphun Warriors on Sunday night.
Buriram have 67 points, 12 ahead of Bangkok who had defeated the Thunder Castle in midweek.
Buriram comfortably tamed bottom club Lampang at Chang Arena thanks to goals from Jonathan Bolingi in the fifth minute and Lonsana Doumbouya after 19 minutes.
Buriram coach Masatada Ishii praised both sides for producing a good game in hot conditions.
"We have moved closer to the title," Ishii said. "We should get the job done in the next game."
The Japanese admitted that his players made several mistakes and needed improvement.
He said the team's target remains a clean sweep of three domestic trophies.
Buriram will meet Port in the FA Cup semi-finals on April 19 and will take on Prachuap in the League Cup last four on April 26.
The league is now taking a break for the Songkran festival and will resume on April 22 when Buriram travel to Chiang Rai United.