Gold favorite, Iran, overcame Vietnam through Seyyed Jalal Hosseini's solo goal four minutes into the game on Saturday.
The victory secured the team's surge to the last 16 of the competitions. Iran tops the group with 9 points followed by Turkmenistan and Vietnam with 4 and 3 points respectively.
In the other Group B match, Bahrain drew level with Turkmenistan 1-1.
Earlier, the Iranian outfit thrashed Turkmenistan 4-1 and Bahrain 1-0 in the previous Group B matches.
Iran, coached by Gholamhossein Peyrovani, takes on Malaysia on Monday for a place in the quarterfinals of the event.
In other matches on Monday, Oman faces Hong Kong, Qatar meets Uzbekistan, and China clashes with South Korea.
Japan-India, North Korea-Vietnam, the UAE-Kuwait, and Turkmenistan-Thailand will hold Tuesday's matches.
The 24-team Asian tournament began in Guangzhou on Sunday, with the teams divided into six groups of four.