"I feel pressure playing against North Korea. We are the same people and we speak the same language, but politically we are not very friendly at the moment," said Yoo Nam Kyu, coach of South Korea's men's team, through a translator.
South Korea came through Saturday's first round team match 3-1, a far closer win than had been expected for the tournament's second seeds, against their 11th seeded rivals.
Victory was sealed by South Korea's 2004 Olympic champion Ryu Seung-min, who beat Kim Hyok-bong in a close game just nine months after they had lined up alongside each other as team mates at the Qatar Peace and Sport Cup.
"We always say hello, there's no problem, table tennis is special," said Ryu after the game. "We have a good relationship and good friendship. But on court we are at war, table tennis war."
Ryu and Kim Hyok-bong shook hands at the end but there was little talk or contact between players of coaches throughout. Ryu and Yoo said they greet and speak to their rivals, but just about sport and their condition, never straying into politics.
North Korea's coaches and players refused to stop in the media interview area after the match.
Table tennis is one of the most popular sports in both countries and has in the past led sporting efforts to bring the two nations closer.
In 1991 Korea competed as a single team at the table tennis world championships, using a Korean "Unification Flag" for the first time, just three years after the North had boycotted the Seoul Olympics.
South and North Korea marched together at the opening ceremonies of the 2000 Sydney and 2004 Athens Olympics, though they competed as separate teams.
South Korea is Asia's fourth biggest economy and has some of the region's highest living standards, whereas the North is an isolated state that has strict controls over any form of communication, a decaying economy and chronic poverty.
Tension between the two Koreas spiked after a torpedo attack in 2010 many believe was launched by North Korea sunk a South Korean navy ship killing 46 sailors. Pyongyang denies its role.
The North bombed a South Korean island later in that year killing four people in the first such attack on South Korean soil since the war.
Indeed, the two countries are technically still at war as no peace treaty was ever signed after their 1950-53 war and the border between them is the most heavily fortified in the world.
North Korea, playing in red and blue, raced to a surprise early lead when Kim Hyok-bong, ranked 77 in the world, beat Oh Sangun, ranked 11th.
The South, playing in black with flashes of white, blue and red and fielding one of the tallest team's in the sport, bounced back with a win in the next singles game and a pivotal doubles win, setting up Ryu to take the decisive game.
The table tennis duel came a week after South Korea's flag was mistakenly shown before the North's women played a soccer match, and North Korea's table tennis coach last week complained to organisers in London that photographers from the South had disrupted his training session.
Winning North Korean athletes can face a life of luxury when they return, receiving cash, cars, houses and the coveted membership of the Workers Party of Korea, and typically praise their nation or leader after victory.
The consequences of sporting failure are far less palatable. A South Korean newspaper quoted an intelligence source as saying those who performed badly could be sent to prison camps, though that has been disputed by North Korean athletes.