Although Viettel only needed a draw in the last game of group I to advance, the Hanoi-based club still fielded their strongest lineup. Hougang also put their best players on. However, the game on HCMC's Thong Nhat Stadium was affected by heavy rain before kickoff.
While Viettel attacked from the outset, it was Hougang that scored first off a penalty awarded after Nguyen Duc Hoang Minh accidentally committed a foul. Pedro Bortoluzo tricked Viettel keeper Quang The Tai to open the score.
The hosts struggled to find the equalizer until the end of the first half when the drama began. Viettel got a penalty in the 41st minute after a Hougang player committed a handball inside the box. Pedro Paulo successfully converted the penalty and just two minutes later, he scored again from another penalty, also from a handball.
But Viettel could only hold on to the lead for three minutes. The referee gave the fourth penalty in the game to Hougang and Bortoluzo got his brace to tie the game 2-2 at half time.
In the second half, U23 Vietnam player Nham Manh Dung was subbed in and he made an immediate impact. After just 10 minutes on the field, Dung sprinted down the left flank and passed inside the box for Hoang Minh to tap it in.
Viettel dominated the rest of the match, scoring two more goals, both by Geovane Magno. His first goal was a gift when a Hougang defender made a careless pass back to the keeper. The second was a beauty. He won the ball and dribbled from the left flank into the box, past three defenders before finishing into the top corner.
Viettel have finished the group stage with nine points. They will play the knockout round in August.