Hajime Moriyasu's men remarkably finished first in Group E above Spain and Germany, while the 2018 runners-up were forced to settle for second in Group F behind Morocco.
Match preview
It was camera angles galore when Ao Tanaka found himself in the right place at the right time to prod home Japan's second goal in their 2-1 win over Spain, who had taken the lead against the Asian nation before Moriyasu's half-time substitutions paid dividends once more.
Alvaro Morata took just 11 minutes to break the deadlock for Spain before substitute Ritsu Doan's venomous leveller, and fellow half-time change Kaoru Mitoma just about managed to keep the ball in play for Tanaka to settle the contest and book Japan's last-16 place in dramatic fashion.
Any team that beats the 2010 and 2014 world champions in one tournament no doubt deserves a place in the knockout rounds, and Japan have finally broken their cycle of a last-16 place followed by a group stage exit, having also got to the knockout phase in Russia four years ago.
The Samurai Blue are far from the finished product, as evidenced by their disappointing 1-0 loss to Costa Rica on matchday two, but they could now set up an all-Asian quarter-final with South Korea, although their near neighbours must first eliminate Brazil in their last-16 battle.
Japan are still waiting for their first quarter-final appearance at a World Cup and are no strangers to having their backs against the wall - averaging just 32.3% possession in Qatar so far - and Moriyasu's super subs must continue to prove as effective as ever if history is to be made on Monday.
Had Romelu Lukaku been able to finish one of the plethora of gilt-edged chances he inexplicably wasted against Croatia, the Chequered Ones could very well have been heading out of the competition, but the Chelsea attacker's profligacy worked in their favour to the extreme.
Steadfast defending from in-demand RB Leipzig starlet Josko Gvardiol also helped get Zlatko Dalic's side over the line in a 0-0 draw, which saw the 2018 runners-up finish second in Group F behind Morocco and qualify for the knockout rounds by the skin of their teeth.
Putting four goals past Canada is all well and good for Croatia - as is their stellar defensive record, with just one goal conceded in the tournament so far - but they have already failed to score in as many games at this World Cup as they had done in their previous 13 matches.
Nevertheless, the Chequered Ones now come into the last-16 clash on a nine-game unbeaten run across all tournaments and progressed from both of their previous ties at this stage of the competition, but Dalic's side can take nothing for granted against the counter-attacking machine that is Japan.
Since suffering a 4-3 loss in their first meeting with Japan 25 years ago, Croatia have since beaten the Samurai Blue at the 1998 World Cup before playing out a goalless draw in the 2006 edition, and yet another low-scoring affair in Qatar is not beyond the realm of possibility in this last-16 showdown.
Japan World Cup form:
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Japan form (all competitions):
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Croatia World Cup form:
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Croatia form (all competitions):
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Team News
Japan manager Moriyasu witnessed defender Ko Itakura pick up his second yellow card of the World Cup in the win over Spain, meaning that he will be suspended for the last-16 battle, so Takehiro Tomiyasu should come in to deputise after also performing well off the bench in midweek.
Stuttgart midfielder Wataru Endo shook off a fitness concern to come on as a substitute in that game, and right-back Hiroki Sakai has also rejoined training, but Takefusa Kubo is a fresh doubt due to muscular discomfort.
Not for the first time in Qatar, the Japan boss is facing the best kind of selection dilemma in the final third, where Doan has surely done enough to come in for the stricken Kubo, but Mitoma's efforts may not be enough to edge out Daichi Kamada.
As for Croatia, Dalic has already confirmed that he will be working with a fully-fit squad for Monday's match, but veteran pair Luka Modric and Dejan Lovren will miss any potential quarter-final if they are booked here.
Neither man will lose their place in the XI here, though, with Dalic set to stick with his tried-and-tested 4-3-3 formula, but there could be scope for a change or two in the final third.
Andrej Kramaric and Marko Livaja both failed to shine in the goalless draw with Belgium, and Dalic is not short of options in attack, where Bruno Petkovic, Mislav Orsic, Nikola Vlasic and Mario Pasalic are all vying for opportunities.
Japan possible starting lineup:
Gonda; Tomiyasu, Taniguchi, Yoshida; Ito; Morita, Tanaka, Nagatomo; Doan, Maeda, Kamada
Croatia possible starting lineup:
Livakovic; Juranovic, Lovren, Gvardiol, Sosa; Kovacic, Brozovic, Modric; Kramaric, Livaja, Perisic
We say: Japan 1-1 Croatia (a.e.t, Croatia advance on penalties)
With a penchant for lightning quick counter-attacks and a wealth of players in reserve waiting to make a difference, Japan have every right to feel that another shock is on the cards, and finding a consistent attacking formula has not been on the agenda for Croatia.