After a battling display that saw them eke out a 0-0 draw against the 2018 champions at Jalan Besar Stadium, they could still be pleased with a result that does their semifinal prospects no harm ahead of their final Group B clash against fierce rivals Malaysia on Tuesday.
Unfortunately, there is plenty of cause for concern for the Lions after they lost striker Ilhan Fandi to a potentially serious injury -- depleting an already-weakened attack.
Still only 20 and leading the Singapore attack in the absence of star man and older brother Ikhsan Fandi, Ilhan had given a decent account of himself at the tournament thus far, netting in their opening 3-2 win over Myanmar and offering a presence up front.
But when he went down innocuously after a shooting opportunity shortly before halftime on Friday, and immediately clutched at his left knee in agony, things were not looking good.
Ilhan was eventually able to get back on his feet and even tried to play on before ultimately being replaced at the break, which suggests he may have avoided any potential ligament damage.
Still, with just three days to go to their meeting with Malaysia, there is a real chance he might not recover in time to take to the field at Bukit Jalil National Stadium -- leaving Singapore bereft of options of a genuine No. 9.
The valuable point they earned against Vietnam, who are favourites to finish top of Group B, does however mean that the Lions do not necessarily need to beat Malaysia.
A draw would be enough to secure their place in the last four for a second tournament running.
And from the way they resolutely held out against the Vietnamese despite only having 23% of possession, another dogged defensive display is not beyond them -- especially with Nishigaya's preference for a conservative 5-4-1 so far in the tournament.
Nonetheless, playing for a draw from the opening whistle is never the wisest of plans.
Especially against the old enemy, in what will be a hostile atmosphere that could see them also up against upwards of 60,000 vociferous Malaysian supporters, against a team that have already shown an ability to hit the scoresheet in their 5-0 rout of Laos back in their second game.
It is unlikely that Nishigaya will set Singapore out to be completely defensive against the Malaysians.
At the very least, they will be looking to hit on the counter and hold up the ball in attack whenever it enters their final third.
Still, with a possible lack of target-man options following Ilhan's injury, it remains to be seen if they will be able to do just that and secure their place in the semifinals.