Image copyright AFP Image caption South Korea's star player is Tottenham's Son Heung-min

On Tuesday, North and South Korea played a football derby like no other.

It's not too rare for the two sides to face off, but almost unheard of to play in the North's capital, Pyongyang. In fact, it's only happened once, in 1990.

There was no live broadcast, no fans from the South, and no foreign media at all in the stands as the sides played out a goalless draw.

After some progress in 2018 - when sports partly broke the ice - ties between North and South are at a low.

Safe to say, this was a match the home side were not taking lightly.

"Football is the most popular spectator sport in North Korea and sports are hugely important for the North," Andray Abrahamian, senior adjunct fellow at the Pacific Forum, told the BBC before the match.

"It provides a focal point for pride and patriotism. In a sense, it's pretty similar to how other countries use sports for social purposes."

Image copyright Reuters Image caption The North's stadiums are better known for propaganda than for international football

If you wanted to follow the match between the two national men's teams you'd have had a hard time.

Apart from the fact it wasn't broadcast live, even international tourists currently in North Korea weren't allowed to watch the game.

How unusual is a North Korea - South Korea match?

It does happen: both countries are members of Fifa and the Asian Football Confederation, meaning they can be drawn against each other in international competition.

There have also been friendly matches - including that game in Pyongyang in 1990. This time, it was a qualifier for the 2022 Qatar World Cup that brought them together.

But what's rare is that Tuesday's match took place in North Korea.

Previously, most games were held either in the South, or in a third country. When they were drawn against each other in the 2010 World Cup qualifiers, both the North's home games against the South were played in Shanghai, China.

The two countries are technically still at war - the Korean War ended in 1953 with an armistice, but a peace treaty was never signed - and the North would not allow the South's anthem or flag in its stadium.

Image copyright Getty Images Image caption North Korea's women's team (in red) only lost once to the South

The women's teams have also only played once in the North, for a 2017 qualifier for the Asian Cup the following year.

All other women's matches were held either in the South or a third country.

Which side were the favourites this time?

For the men's sides, the odds were clearly with the South.

The team has won or drawn almost every fixture since the first match in the Asian Games in 1978, with the 1990 friendly in Pyongyang being the only time the North triumphed, winning 2-1.

Given the South is ranked 37 in the world compared with the North at 113, you might have expected South Korea to win this one as well.

Yet both teams remain level at the top of their qualifying group, having each won their previous two games. The South are just ahead on account of having scored more goals so far.

Each side has a star player: for the South, Tottenham's Son Heung-min, while North Korea have recent Juventus signing Han Kwang-song.

Image copyright Reuters Image caption North Korea's Han Kwang-song fights for the ball with Lebanon's Nour Mansour at the Kim Il Sung Stadium, Pyongyang, in September

Despite North Korea's home advantage, it wasn't even clear before the match whether there would be any home spectators. Talking to reporters on the way to Pyongyang, South Korean players appeared to expect an empty stadium.

"It's much better to play in a packed stadium rather than an empty one, but I think we'll be able to play a good match if we use it as motivation," defender Kim Min-jae told AFP news agency.

For the women's team, the stats are almost an exact inversion of the men's.

The South has won only once. All other matches were either a draw or won by the North.

What's the state of North-South relations?

The match comes as relations between Seoul and Pyongyang hit another low.

The North is upset that South Korea continues to carry out low-level military exercises with the US, and earlier this summer rejected all further talks with Seoul.

The North's denuclearisation talks with the US have just again hit a roadblock, and relations with the South tend to ebb and flow alongside such talks.

Pyongyang also recently tested a new missile, in a significant advance on earlier tests, increasing tension with Washington.

Media playback is unsupported on your device Media caption The nuclear word Trump and Kim can't agree on

But the ups and downs of North-South relations are not usually reflected in the sporting rivalry.

"The people I've talked to about this in both Koreas generally seem quite supportive of athletes from the other side," says Mr Abrahamian.

"They're pleased to see Koreans doing well on the world stage, whatever country they're from."

Sports diplomacy to the rescue?

Sport has often been a key to unlocking fresh diplomacy on the peninsula.

The 2018 thaw came about when North Korea's Kim Jong-un floated the idea his country could take part in the Winter Olympics in the South.

Months later, the two teams marched under a common flag, participated together and even fielded a joint women's ice hockey team.

The same feat was repeated at the Asian Games when a unified Korea boating team won a historic gold medal.

Image copyright AFP Image caption The gold medallists sang a national folk song to celebrate their victory

With the mood in Pyongyang notoriously unpredictable, it is hard to say whether Tuesday's soccer game might again pave the way for fresh diplomacy.

In September, North and South agreed they would seek to co-host the 2032 Summer Olympics.

But in the lead-up to the World Cup qualifier, relations remained tense.

The South hoped to be able to send fans to the match – but were denied. And Seoul offered to organise the broadcasting of the match, an offer also turned down.

"This time, it doesn't look as if Pyongyang is looking for the match to be a tool to bridge the strained political relationship," Mr Abrahamian said.

"Pyongyang has been giving Seoul the cold shoulder for most of this year and that probably won't change - unless the US and North Korea find a breakthrough."