It is a fierce rivalry born from proximity and shared history, and Singapore's athletes are bracing themselves for loud, intense and partisan home crowds when they face their Malaysian counterparts at this SEA Games.
Tonight will see the arch-rivals clash again in men's football, as Singapore enter the 80,000-seat cauldron that is the Shah Alam Stadium to face Malaysia in a crunch Group A tie.
Yet, the sporting contest between both countries extend beyond just football, as they will also face off in netball and women's water polo group-stage clashes on the same day.
The Causeway rivalry is particularly strong in netball, with Malaysia and Singapore are the only countries to have won gold in the sport, each winning once on their respective home soils in 2001 and 2015.
Netballer Charmaine Soh, 27, experienced this rivalry from the time when she was a national youth player in 2009, and the intensity reached a boil at the 2015 SEA Games in Singapore.
She said that there were even a few instances at the 2015 Games where some Malaysian players tried to intimidate her by shooting her "dirty" looks as they passed one another in common areas.
They might boo us every time we shoot, so I've been doing this 'noise training' while trying to concentrate and shoot.
CHARMAINE SOH, on how she is adapting to the electrifying atmosphere.
Such incidents were proof of how much the Games gold meant to Malaysia's netball team, and it turned out to be the fuel that fired Soh up, despite being "furious" by their antics at first.
"We had been beating Malaysia quite consistently (before the 2015 SEA Games), as their players were young and they were still building up their team," she said.
"They became tougher and stronger in recent years and I think in 2015 they knew it and wanted to retain the gold."
To cope with the probability of a less-than-friendly home crowd today, the goal shooter has been resorting to practising with a lot of noise in her ears.
She added: "They might boo us every time we shoot, so I've been doing this 'noise training' while trying to concentrate and shoot.
"I've been listening to a lot of crowd noises and booing noises, which might happen because it's at their home ground."
While the netball contest between the two countries grew in recent times, their football rivalry is far more historic, and has occasionally manifested in unpleasant ways, such as the scuffles that broke out between fans at the 2012 Causeway Challenge at this same stadium.
In the 2015 Malaysia FA Cup semi-final clash in Terengganu, the LionsXII team and their fans were trapped in the stadium for close to five hours as angry Terengganu fans rioted outside.
SEA Games captain Shahrin Saberin knows how impassioned this rivalry can get, as he said: "I've heard (from senior footballers) that it is very intense because even if we beat Malaysia in a friendly match, everyone will be talking about it, including those who don't normally watch football."
The national Under-22 defender is confident there will be no such violence or animosity today, adding: "I will be expecting a warm reception from the fans and players because we have built a good, friendly relationship with one another.
"Of course the Malaysian fans will support their own team because they are playing at home, but we just need to shut all negative thoughts out and focus on our job in getting those crucial three points."
Women's water polo captain Gina Koh acknowledged that the local spectators at the National Aquatic Centre will be backing their team in full force today, but doubts there will be any hostility from the audience.
"It's sportsmanship, I don't think any crowd will (boo)," she added.
In other sports such as bowling, the Causeway rivalry is also no less competitive.
For Singapore's women's bowling team, the memory of losing the 2015 SEA Games gold to their Malaysian opponents by a mere 55 pinfalls, after a battle that lasted almost nine hours, still lingers.
The quintet of Jazreel Tan, New Hui Fen, Shayna Ng, Cherie Tan and Daphne Tan had taken "more than just a while" to recover from that loss, according to Ng.
She added: "(The loss) was quite painful, but the mindset that we're going into this SEA Games (with) is what doesn't kill you makes you stronger.
"We are hungrier than ever and we have been putting in a lot of effort at training to better prepare ourselves for what's coming."
Malaysia topped the medal table for bowling at the last edition with five golds, one silver and four bronzes, while Singapore were second (four golds, five silvers, one bronze).
Still, Ng does not consider the relationship between both nations a rivalry.
The 27-year-old explained: "Our main goal is not to beat Malaysia, it's more to display our fullest potential because if we all play our part, we'll be able to display our best (performance).
"I don't think there is a rivalry but I think it's also good that Malaysia are challenging and an obstacle to overcome. It's always good to have challenges that we face together as a team, so that we can grow."