Separated by a body of water a mere kilometre wide, their histories intertwined but their football tribes divided, there will be no holds barred when the big cats of Singapore and Malaysia battle tonight at the National Stadium.
A place in the Asean Football Federation (AFF) Suzuki Cup semi-finals is at stake before what could well be a sell-out crowd.
Over 45,000 tickets in the 55,000-seat arena had been sold as of yesterday.
So the stage is set for Singapore coach Bernd Stange's biggest test so far in his 18 months in charge.
The German has led his charges against quality Asian teams like Oman and Syria.
But nothing gets Singapore fans going like a win, or a loss, against arch-rivals Malaysia.
Said the 66-year-old:. "It'll be a packed stadium and I am quite excited to see this match and I hope the team can win the hearts of the Singaporean football fans."
Malaysia's morale was deflated on Wednesday after conceding a last-minute winner in their 2-3 loss to Thailand. The Tigers need to beat Singapore and hope Myanmar do not beat Thailand or improve on their -2 goal difference.
"We desperately need a win," said Malaysia coach Dollah Salleh.
"It won't be easy with more than 40,000 Singapore fans. But we will try to give something to the Malaysians."
In an unusual move, the Tigers imposed a media blackout ahead of yesterday evening's training session at Bishan Stadium.
It is not known if it was linked to a picture of key player Safee Sali allegedly smoking making its rounds on social media.
Dollah declined comment while the Johor Darul Takzim striker side-stepped the issue, saying: "I am focused on the match."
Things are more serene in the Lions den. "They need the win so they are going to attack for sure," said captain Shahril Ishak.
"We have to be smart about it and not do anything stupid, like give the ball away in key areas or commit silly fouls in our half."
The Lions will be without two key players as centre-back Baihakki Khaizan is suspended while midfielder Shahdan Sulaiman is out with a broken leg.
Stange is keeping mum on his replacements but it is likely that the pacy Shakir Hamzah will deputise in defence while Zulfahmi Arifin will start in midfield.
But if he opts for safety first, he can deploy key midfielder Hariss Harun in Baihakki's place.
Whatever the permutations, the goal is clear: Lose and the Lions will be out. In fact, a loss in this fixture has traditionally led to more serious consequences.
Dane coach Jan Poulsen lost his job shortly after the 2002 AFF Cup campaign, with a 0-4 loss to Malaysia at Kallang widely believed to be the main reason for his departure.
Stange is not entertaining any thoughts of complacency.
"You never know what will happen in football," he said.
"We shouldn't be so arrogant as to think we are already (in the semi-finals). Malaysia are wounded animals - that's why they are very dangerous."
Added left-back Shaiful Esah: "The most important thing is we all stay calm and not let the occasion faze us. The rivalry is a big thing and it will be a big crowd but we have to shut everyone out and focus on getting a result."
Singapore v Malaysia MediaCorp okto, mio TV Ch114 & StarHub Ch208, 7.55pm