The players may not have experience of Europe's top leagues and, unlike their opponents, they cannot call on the services of a striker who commanded a Dh45 million transfer fee only last summer.
But Vietnam believe they will have a secret weapon when they take on Japan in their Asian Cup quarter-final tomorrow night – their passionate fans.
Groups of committed Vietnamese supporters cheering on the Golden Dragons, as they are known in Hanoi, have become one of the most colourful additions to the Asian Cup.
The community of about 8,000 Vietnamese, mostly living in Dubai and many of them construction workers, are so committed they make home-cooked meals for their heroes.
When word got out that some members of the squad were struggling with food provided in their five-star hotel, supporters stepped in.
They cooked traditional dishes, such as pho and bun cha and tried to deliver them to the players.
Hotel policies prevented the food getting through but their efforts were praised by Park Hang-seo, Vietnam's South Korean coach.
"This is a unique gesture from the fans and we appreciate this kindness," Park said.
Vietnam's win on penalties over Jordan on Sunday was greeted with jubilation from supporters inside Al Maktoum Stadium, and in Vietnam, where street parties broke out across the country.
More than 2,000 fans from Vietnam and hundreds more of Vietnamese descent who are living in other parts of the world are expected to fly to Dubai for the quarter-final.
Sending food was a sign of national pride among the UAE’s Vietnamese, says Van Tran, who has been based in Dubai for 12 years.
Mr Tran runs a successful consultancy and also works in his spare time to promote Vietnamese culture, produce and businesses through the Vietnam Business Association Dubai.
“I am aware that some of the fans were cooking food and trying to get it to the players,” he said.
“Vietnamese rice is available in the UAE, but in the hotel it’s very difficult for them to find traditional Asian food.
“The food in the buffet or on the menus is customised to suit the palate of expats.
“The food didn’t pass the hotel restrictions, but it shows the pride in being connected to the national team and how the fans are trying to support them in any way that they can.”
Tomorrow's game will be an important forum for Vietnamese expatriates to celebrate their heritage and mix with people with Vietnamese roots who live in other countries.
"Having the Asian Cup festivities in the UAE makes us feel at home," Mr Tran said. "In the stadium it is amazing.
“In the first two games we lost but we were still cheering and were happy. It was more a community celebration.”
Meanwhile, at the Vietnamese Embassy in Abu Dhabi, staff are preparing for an influx of citizens.
At the building’s reception, a large display shows the times and dates of the three group games, which many thought would be the extent of Vietnam’s involvement in the tournament.
They lost their first two games, against Iraq and Iran, before overcoming Yemen. It was only because they had received one yellow card fewer than Lebanon that Vietnam progressed to the knockout stages.
“For the coming match with Japan, there will be lots of people coming from Vietnam,” said Nguyen Thanh Quang, first secretary of the Vietnamese embassy, who has attended all four matches so far.
Mr Quang believes at least 1,000 people would pay about Dh4,400 for the air fare alone, despite Vietnam being a relatively poor country.
He thinks that 10,000 Vietnam supporters will be at the Japan game.
One company hired a private jet to send supporters to the game against Jordan free of charge.
Mr Quang has been offered a VIP ticket by organisers for the quarter-final but would sit with his compatriots.
He has a video on his phone of wild celebrations after the win on penalties over Jordan.
“At home they are celebrating everywhere in the street,” Mr Quang said. “Even our Prime Minister has sent a letter to the football team here.
“Football is very popular in Vietnam, the most popular. Every time they play in Vietnam, the stadium is full.”
He said the embassy was aware of the food problem.
"They had a problem with the hotel policy," Mr Quang said. "They don't accept food from outside.
"Here the difference is the rice – they don't cook it, they boil it. And it's basmati. We use different rice.
“It was not restaurants sending it – just the fanatical fans. Whatever they need, they will try to send it immediately.
“We tried to help but it was impossible.”
The ambassador, Dr Trinh Vinh Quang, is in daily contact with the national team liaison officer to see if he can do anything to help.
In his quarters, usually used to entertain dignitaries, a football sits on one of the tables.
The embassy arranged for about 500 UAE-based supporters to greet the team when they touched down in the country.
Despite Japan being the overwhelming favourites in the tie, as well as a strong contender for the Asian Cup title, the ambassador hopes Vietnam will reach the final.
Dr Quang believes the side are underrated and the country has experienced recent success in football.
In December, they lifted the AFF Championship, contested between nations in South-East Asia, and he praises the tactical nous of the coach and adaptability of the players.
“Their hearts are warm and we can dream,” Dr Quang said of the Vietnamese fans.
“It is a busy time but it is my duty to do whatever I can to help.”
