19:00 BST, Monday 2nd July, Rostov Arena (Rostov-on-Don, Russia) BBC One
As one of three teams with a 100% record from the group stage and the highest ranked European side left in the tournament, Belgium are huge favourites coming into this game.
Having scored nine goals in their three World Cup fixtures, Roberto Martínez’s side have netted more than any other nation.
They’ve also kept two clean sheets to accompany their prowess in front of goal, though they’re still short of reaching the potential many expect from this 'golden generation' of players.
By contrast, Japan have no expectations of success hovering above their collective heads. A change of manager just 71 days before the World Cup began saw the relatively inexperienced Akira Nishino take control of the team’s fortunes. Following a defeat to Poland, Japan only just sealed their passage from Group H, having to rely upon their superior disciplinary record over Senegal.
A technically proficient team, the Blue Samurai have shown a strong mentality and will now look to cause another shock in what’s already proven a World Cup full of surprises.
Last Time Out
England 0-1 Belgium
The Red Devils sealed pole position in Group G with a narrow win over England in a subdued match in Kaliningrad. With both teams already qualified for the knockout stages prior to kick-off, a swathe of changes saw 17 of the 20 outfield players replaced from the team’s previous match.
Only Dedryck Boyata and Chelsea goalkeeper Thibaut Courtois retained their place in the team as Martinez stuck by his word to rest key players. After a slow start to the match, Belgium’s strength in depth came to the surface.
Adnan Januzaj scored just after halftime with a moment of magic, shimmying past the otherwise impressive Danny Rose before sending a curling shot into the top corner of the net.
England too had some good chances to score, however, Belgium looked the more assured side and appeared to be playing well within their means. In Marouane Fellaini they also had the best player on the pitch and will have gained plenty of confidence to take with them into the latter stages of the competition.
Japan 0-1 Poland
Japan were left relying on circumstance as they fell to a limp defeat to Poland which eventually proved just enough.
Going into this match Japan were favourites to progress from Group H, however, their performance left much to be desired. Poland’s two previous losses meant they were already eliminated, but they were the better team on display in the Volgograd Arena.
Jan Bednarek side-footed the ball into the net from six yards out with half an hour remaining, a goal which at the time meant Japan were heading towards the exit.
A Colombian goal scored 400 miles away against Senegal 15 minutes later meant Japan were given a reprieve. Rather than ensure their own safety, Japan chose to see out the final 15 minutes of their game by keeping possession within their own half of the pitch.
A complete lack of ambition proved to be a fruitful tactic, if an unpopular one, as their fate was finally sealed two minutes after the final whistle was blown.
There will be a return to a familiar starting XI for this game with the likes of Romelu Lukaku, Eden Hazard, Kevin De Bruyne, Jan Vertonghen and Dries Mertens all expected to be restored to the first team.
After naming an unchanged team to face Tunisia following the win over Panama, Martinez is highly likely to play his favoured starting XI for the third time at this World Cup.
After making five changes for the previous match, Akira Nishino will switch back to a 4-2-3-1 formation, but there’s likely to be one major change from those lineups.
Shinji Okazaki limped out of the defeat to Poland only 90 seconds into the second half with Shinji Kagawa expected to replace the Leicester City forward.
Key Battle: Thomas Meunier (Belgium) vs Takashi Inui (Japan)
Amongst the many Premier League players in the Belgium squad is a player for Paris Saint-Germain who could prove just as influential for their team. Meunier is a natural right-back in a team which is widely considered to be defensively light.
Given more freedom to attack in Martinez’s 3-4-3 system, Meunier claimed five goals and seven assists from the eight qualifying games he was involved with on the road to Russia.
It could be his defensive capabilities which are will come to the fore in the last-16 clash as he’s set to face Japan’s most dangerous player. Takashi Inui impressed during his first World Cup appearance when they beat Colombia, but it was his goal and assist against Senegal which truly announced him on the World stage.
The left-winger - who plays for Real Betis - has been Japan’s best player by far in this tournament and will be their most likely source of a goal, which will be needed if they’re to defeat the Belgians.
These two teams recently played each other and Belgium’s narrow 1-0 win could provide a small psychological edge in this clash. During the friendly in Bruges last November, Lukaku became the country's all-time leading scorer.
It was a match which saw Belgium take their unbeaten run to 15 games and a repeat of that scoreline will extend this to 23 matches undefeated.
With more than half of the starting lineups expected to be identical between the two meetings, these teams have already had the perfect chance to size each other up in the flesh.
Rags to riches
Amid the drama of Japan’s comically ironic fair play passage to the round of the last-16, there was a hidden story of redemption. Eiji Kawashima was the goalkeeper who gifted Senegal an opening goal in the previous match - his weak punch beating him after it rebounded from Sadio Mane’s shin.
Given no chance with Poland’s goal in the final group game, he did make several vital saves to keep his side in contention.
None were more impressive than the scrambling one-handed save he made from Bartosz Bereszynski’s shot after half an hour and it’s possible he may have made the best save of the World Cup.
Prediction: Belgium 3-1 Japan
Japan are unlikely to be the easy target many expect Belgium to face. They have a team full of experience and while they lack pace, they are good in possession and work hard to regain the ball when without.
Belgium possess the firepower to win this game with a small cushion, but won’t necessarily keep a clean sheet on their way to victory.
Listen to the RealSport football writers discuss all the action from Day 15 of the World Cup in Kremlins in the Basement: RealSport’s daily World Cup podcast.