But considering the Vietnamese strikes came from a counterattack, a deflected long-range effort and an own-goal, perhaps the result was not as dire as the scoreline suggested -- even if the result was inarguably a fair one.
Ultimately, as the Lions fell to a second consecutive defeat following an opening loss to Thailand by the same score, their quest to qualify for the semifinals -- which already looked trying prior to the start of the tournament given they found themselves in the perceived Group of Death -- could already be over.
Yet it will not be for a lack of effort especially on the part of coach Philippe Aw and goalkeeper Aizil Yazid.
Unlike on Sunday, when they were outplayed by an exciting and clinical Thai outfit that were just too good, Singapore looked a good chance to keep Vietnam at bay -- at least for much of the first half.
Given Singapore's status as the underdogs, there was no shame in Aw once again opting for a conservative 4-5-1 formation but the intent to press their opponents was well executed by his determined charges and prevented the Vietnamese from finding any passing rhythm early on.
Instead, the breakthrough -- when it finally did arrive in the 36th minute -- came from a counterattack as Le Van Do charged down the left before setting up Nguyen Van Tung to squeeze a shot in at the near post.
While goalkeepers are often liable when beaten at their near post, it was indeed a fine finish that Aizil probably should not be held accountable for.
In any case, the Singaporeans were already in debt to their promising 18-year-old custodian for still being level at that point following a couple of smart saves prior to the opening goal.
Just like he did against the Thais, Aizil's composure and ability in goal belied his tender years and he is already emerging as one real positive from the campaign.
Even if he felt that he could perhaps had given a better account of himself to keep deny Van Tung, there was nothing he could do to prevent Nguyen Thai Son from doubling Vietnam's advantage two minutes before halftime when the midfielder's speculative effort took a wicked deflection en route to nestling in the back of the net.
One player who should have done better in the build-up to that goal was Fathullah Rahmat, whose woeful first touch under no pressure led to the opening for Thai Son to fire away.
Introduced to the Singapore starting XI in favour of Ajay Robson, Fathullah was lucky to even still be on the pitch after accumulating cynical fouls at will in a short span of time -- including a reckless studs-up challenge on the ankle of an opposition defender that could have easily seen him shown red.
To their credit, the Lions did show renewed spirit after the break but any hopes of a late fightback were extinguished in the 80th minute courtesy of another individual error as Ilhan Noor -- panicking when a cross landed in his vicinity despite having no opponent close by -- could only divert the ball into his own goal.
Singapore did grab a consolation in injury-time although it was more a case of it being gifted to them as Vu Tien Long decided to outdo Ilhan, slicing his attempted clearance and sending it looping over his goalkeeper from all of 18 yards.
Nonetheless, as much as Singapore were fortunate to get on the scoresheet at all, they were possibly unlucky to even have been down by three goals in the first place.
The fact of the matter is that, although the Singaporeans may already be out of the running, they have not been as bad as results suggest.
Some of the team will emerge from the tournament with credit to their names regardless of their final standing, and Aw and Aizil look like they will be top of their list.
It was always going to be an uphill battle to advance out of the group stage.
Unfortunately for Singapore, confirmation of that may come sooner rather than later after individual errors undid plenty of their good work against Vietnam on Wednesday.