Following a goalless first half at the Viet Tri Stadium, Vietnam took the lead nine minutes after the break when Nguyen Tien Linh spread play out wide before racing into the area to apply the finishing touches to an incisive move down the left.
The tournament hosts then doubled their lead in the 74th minute when Tien Linh turned provider as another of Vietnam's overage players stepped to the fore -- Do Hung Dung breaking free inside the area after a lovely one-two with the striker before prodding a shot past Adi Satryo.
And with three minutes remaining, the Vietnamese put the result beyond doubt with a third as Indonesia defender Fachrudin Aryanto completely missed his attempt to clear a low ball into the area by Le Van Do to allow the ball to make its way into the bottom corner past a confounded Adi.
Philippines smash Timor Leste in Group A opener
Philippines cruise to a 4-0 win in their Group A clash with Timor Leste at the SEA Games.
Christian Rontini got Philippines up and running with a close-range header after ten minutes, before second-half goals by Dennis Chung, Jovin Bedic and Oskari Kekkonen completed the rout.
The Group A action continues on Sunday with Indonesia looking to bounce back against Myanmar, while Vietnam will be expected to make it two wins in a row against minnows Timor-Leste.