Robert Alberts' PSM Makassar blew the Indonesian title race wide open on Thursday night with a 2-0 win at the home of Liga 1 leaders Bhayangkara.
With four games of the season remaining, the Sulawesi team moved into second, and a point behind Bhayangkara, who have now lost two successive league games just when a first title had moved into sight.
Both goals came early in the second half and both came from corners.
Wiljan Pluim opened the scoring three minutes after the restart. The Dutch midfielder reacted quickly at the near post to turn Zulham Zamrun's right-sided set piece into the net.
Just two minutes later, PSM extended their advantage from another corner. This time, it was from the opposite side as Steven Paulle's header eluded the hosts' defenders to roll over the line.
The leaders battled to get back into the game. Ilham Armaiyn came the closest for the home side as the substitute fired over the bar with 10 minutes remaining.
The win revived the title hopes of PSM. The early season leaders, coached by ex-S.League and Malaysia Super League boss Alberts, are now just a point off the pace,
"We had looked at how Bhayangkara played before the game and we came up with a good performance," Alberts said. "Both goals came from set pieces, but we were looking to score as often as we could."
The result is a major blow for Bhayangkara, though British coach Simon McMenemy denied that the team are wobbling with the title within reach.
"We played well, had plenty of possession but were just not able to score," McMenemy said. "It is frustrating to lose due to two set pieces, but there are still four games to go, and we are in a good position."
The title hopes of Madura United faded further, thanks to a 0-0 draw at Persib Bandung.
Madura are in fifth, four points off the pace while big-spending Persib are languishing in 11th. Madura still have a chance to return to the title race as they host Bhayangkara on Monday.
Elsewhere, Mitra Kukar won 2-1 at Semen Padang while Borneo defeated Persela 4-2.
Bali United can move above PSM into second on Friday with a win against PS TNI.