Thawatchai Dumrong-ongtrakul announced on Wednesday he had quit as coach of Thai League 1 side Nongbua Pitchaya.
The former Thailand international is the third T1 coach to lose job this season.
His departure came after Khon Kaen United parted ways with Carlos Eduardo Parreira at the weekend and Makoto Teguramori left BG Pathum United last week.
Thawatchai's resignation was not a big surprise as Nongbua are last in the league with only four points after 11 games.
"I'd like to apologise to the fans for failing to guide the team to our target," said Thawatchai, whose team lost to Lamphun and Police Tero in their last two matches.
Nongbua chairman Suthep Poomongkolsuriya said: "In the last two matches, we played teams at the same level with us but could not get a single point. We did not expect that and we need changes.
"The team still have a good structure but the players lack confidence."
Thawatchai, 48, joined Nongbua last year and steered the club to sixth place in their first ever season in the top flight.
However, Nongbua have failed to deliver after the departure of several players during the close season, particularly striker Hamilton Soares, the league's top scorer last season.
Nongbua are at home to Prachuap in T1 on Sunday.
Phairoj to coach Cobras
Thai League 1 strugglers Khon Kaen United have appointed Phairoj Borvonwatanadilok as their new coach.
Khon Kaen chairman Wattana Changlao said: "It's time for changes to make the team better. Coach Bae [Phairoj] is a good coach and have a lot of experience. We are ready to work harder to bring happiness to our fans."
Phairoj, 55, has coached several clubs including Samut Prakan, Sukhothai, Suphanburi and Muang Thong United.
He coached Chiangmai FC before joining the King Cobras who host Muang Thong in T1 on Sunday.