Arthit Sunthornphit and Anon Sangsanoi each scored twice as three-time winners Thailand swept aside Laos at the Surakul Stadium in Phuket to secure their second consecutive win at the AFF Suzuki Cup.
Thailand coach Peter Reid opted to field a largely second-string side for the Group B tie, but the hosts still dominated, racing to a 3-0 lead at the break with goals by Ronnachai Rangsiyo, Patiparn Phetphun and Arthit.
Arthit netted his second with a free-kick early in the second half before Anon completed the rout with a pair of goals in the final 11 minutes.
The Thais moved to the top of the group with six points and all but sealed their place in the semi-finals barring a heavy loss to Malaysia in their final group game on Wednesday.
Reid made 10 changes to the side that started in the 2-0 victory over Vietnam on Saturday with Suree Sukha the only player to start both matches.
But the Thai reserves took control from the opening whistle and nearly went ahead in the 13th minute when goalkeeper Sengphachan Bounthisanh spilled a free-kick by Arthit on his goalline, only for Chandalaphone Liemvisay to hack the ball clear before Rangsan Vivatchaichok could pounce.
Laos held out for 68 minutes in their 3-0 opening loss to Malaysia, but their resistance was broken by the Thais after only 19 as Suree surged down the right and cut the ball back for Pichitphong Choeichiu, whose shot was stopped by Sengphachan but bobbled towards the goalline where Ronnachai slid in to apply the final touch.
Anon sent a header just wide shortly afterwards and Sengphachan did well to tip Rangsan's effort over in the 29th minute.
On the resulting corner, the Laotian keeper denied Suree from point-blank range but his defence failed to get enough distance on the clearance allowing Patiparn to lash home Thailand's second from the top of the box.
Arthit extended the advantage five minutes before the break, curling a superb free-kick from 25 yards into the top right corner that gave Sengphachan no chance.
He was more fortunate with his second goal seven minutes into the second half as he floated in a free-kick from the right that flew over a sea of heads and settled into the far corner of the net without taking another touch.
The Thais made it 5-0 in the 79th minute when Ronnachai's shot deflected off a defender to an unmarked Anon, who easily dispatched the ball past a helpless Sengphachan.
And the forward grabbed his second a minute from time, rising above the Laotian defence to head home a Rangsan free-kick.