Belgium eventually eased their way past Panama then made light work against Tunisia in their opening group games. They qualified as Group G winners after beating England 1-0 in a game they made wholesale changes for.
Japan secured qualification from their group in the most extraordinary manner. They were level on points, goal difference and head-to-head record with Senegal who were in the last ten minutes of their game against Colombia. Those standings remained the same and Japan edge through as Group H runners up due to picking up less yellow cards than Senegal.
The sides met in a friendly match in November 2017 where Romelu Lukaku scored the only goal of the game.
Follow all the action in the live blog below
What time is it?
Belgium vs Japan kicks off at 19:00 at the Rostov Arena.
Where can I watch it?
BBC will be showing live coverage on BBC1 and online on the BBC Sport website
Draw (90 minutes): 7/2
Belgium 2-0 Japan. Japan have been extremely well drilled in their group games but are unlikely to have the individual quality to cope with Belgium’s impressive playmakers and forwards.
Good morning and welcome to our live coverage of the 2018 World Cup.
The last-16 continues in Russia today with two mouth-watering clashes.
First up we'll see Brazil vs Mexico before Belgium take on Japan a little later on.
We'll have all the build-up and action from Rostov right here.
Assuming Belgium can overcome Japan, tournament favourites Brazil are their likely opponents in the quarter-final. Either a solid and effective Uruguay or an ultra-talented France would then await in the last four. If Belgium reach the final at the Luzhniki Stadium in just under a fortnight’s time, their place there will be well deserved.
Whether much attention should be paid to permutations is a matter for debate – as many in England learned this week – but Martinez’s opinion on the matter was always clear.
He was aware this could be the case before Kaliningrad and made no secret of his preference. His remarks to the contrary after the win – claiming to be “delighted” with topping the group – sounded slightly disingenuous given what had been said before. Spain’s elimination has since fully opened up the supposedly ‘easier’ side.
There was a sign on Sunday, though, that Martinez had learnt his lesson. At his pre-match press conference, he chose not to look too far ahead again. Belgium should beat Akira Nishino’s limited Japan handily in Rostov on Monday night, but Roberto Martinez is staying grounded and taking nothing for granted.
Today's first game is just about to get underway in Samara.
It's Neymar vs Hernandez, Coutinho vs Herrera, Brazil vs Mexico.
You can follow that one live here:
It's over to Rostov now, where Belgium and Japan will battle it out for the right to meet Brazil in the World Cup quarter-finals.
Belgium are heavy favourites, and it's easy to see why. They are unbeaten in their last 22 games (17 wins, five draws), a stretch dating back to September 2016. Japan, meanwhile, only made it into the round of 16 at Senegal's expense by virtue of their superior fair play record.
Will we see another huge upset, or will Belgium maintain order to set up one of the most mouthwatering clashes of the World Cup so far?
Both teams have been announced and, unsurprisingly, all of Belgium's big guns are back after resting against England.
If Japan are to cause a monumental upset, nullifying Romelu Lukaku will be the top priority for coach Akira Nishino. The Manchester United striker has scored 23 goals in 20 appearances for Belgium since Roberto Martinez took charge, and has converted all of his four shots on target in this World Cup.
The big news from Belgium's starting XI is that Vincent Kompany makes his first start of the tournament in defence. Martinez took no chances with the Manchester City captain in the group stage to ensure he was physically ready for World Cup knockout football, and now it is time to find out whether or not his body holds up.
Having watched Brazil ease into the quarter finals against Mexico, Belgium will be hoping for a similarly simple passage with victory over Japan.
The Japanese have made headlines due to the manufactured style of the closing minutes of their game against Poland, but although the underdogs here, they have the ability to frustrate, and cause problems of their own with discipline and accurate passing. Attacking midfielder Takashi Inui has looked particularly creative so far.
For those of you cultured to the Premier League style, tuning in every week and watching in grounds across the country, this Belgium side is pleasant viewing.
With seven of the starting XI plying their trade in the Premier League, these players are household names, and they come with a pretty big burden of Belgium's golden generation. Add to that the likes of Manchester United's Marouane Fellaini and Chelsea's Michy Batshuayi they have strength in depth too, and that could pose a real problem from the bench if scores remains level close to the end.
In the much talked about draw of this World Cup, Belgium find themselves in the so-called 'harder' half after their 1-0 victory over England. But part of that harder half, was an expected easier round of 16 tie against the unfancied Japanese, instead of a dangerous Colombian side.
Will Belgium live to regret that victory over England? Remember Japan beat Colombia in their group game - albeit with the help of an early red card for Colombia's Carlos Sanchez
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