MOSCOW — Three weeks remain in this World Cup, three more weeks of stoppage-time stunners, goalkeeping howlers and video-replay reversals until the billion-people-are-watching final kicks off at Luzhniki Stadium on July 15.

A strong case can be made, though, that some of the most dramatic moments will play out over the next four days, perpetrated in some cases by teams that will head home by the end of the week.

We have reached the last round of the group stage, and unlike the previous set of matches, respective group games will kick off simultaneously.

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The purpose is to minimize chicanery; the result, however, is 90 minutes of high anxiety, obsessive smartphone-checking and abrupt turns of fortune at, in some cases, two tense venues hundreds of miles apart.

Take, for example, Mexico, which sits atop Group F with six points and seems certain, on the surface, of advancing to the round of 16.

If El Tri falls behind Sweden on Wednesday in a venue near the boundary between Asia and Europe, Mexican supporters will want to closely monitor the status of the Germany-South Korea match unfolding 600 miles to the west.

Six teams — Russia, Uruguay, France, Croatia, England and Belgium — have already secured passage and are playing to learn their next destination and opponent. One superpower (Argentina) must win. Four titans (Brazil, Spain, Portugal, Germany) are not out of danger. And a fairy tale (Iceland) is on the brink of ending.

Here’s a closer look at the eight groups:

GROUP A

Russia and Uruguay have already clinched, at the expense of Egypt and Saudi Arabia. Both sit on six points, but the hosts are ahead, thanks to a superior goal difference, and need only a draw against the South Americans on Monday in Samara to win the group.

When the tournament started, Russian fans feared the embarrassment of group elimination. Now, with a victory or draw, the Russians would finish unbeaten and rule the group.

Does first or second place matter? From a competitive standpoint, it probably doesn’t because, either way, Russia’s opponent is likely going to be Spain or Portugal. What’s important is sustaining momentum, retaining form and continuing to galvanize a nation that stands in the world spotlight this summer.

Russia has not yet been tested in this soft group, and a victory over an established side would do wonders.

GROUP B

Spain and Portugal are even on points (four) and goal difference (plus-one). But heading into Monday’s games, the Spaniards have the advantage because they play a team that’s been eliminated (Morocco) while Cristiano Ronaldo and Co. face an opponent (Iran) with three points.

An upset in Saransk would propel Iran into the next round, perhaps win the group and possibly eliminate Portugal. A Spanish victory is far from certain. Despite failing to earn a point, the Moroccans have played quality attacking soccer and deserved better in their first two matches.

With berths unsecured, none of the three contenders are concerned about the potential next foe. That said, what would they prefer: a Russian team with home-field advantage or a side from Uruguay that poses greater danger?

GROUP C

France is through to the round of 16 and, with a victory or draw against second-place Denmark on Tuesday in Moscow, would seal first place. Is Didier Deschamps’s squad a genuine championship contender? We just don’t know yet. His squad has been good but not great. A quality European side provides a good test.

The Danes (four points) are unbeaten and on course to finish second with a draw, but if they fall behind, they will have to remain mindful of the Australia-Peru match in Sochi. The Aussies (one point) could pull level with Denmark on points (and pull ahead on goal difference) by defeating Peru.

Here’s the thing, though: Although the Peruvians have been eliminated, they are more talented than Australia. By remaining motivated in their first World Cup appearance in 36 years, the Peruvians could end the Aussies’ distant hopes.

GROUP D

There was no reason to project France’s next opponent because the situation in this group remains too unsettled. We know Croatia (six points) is almost certain to finish first. The only team that can catch up is Nigeria, but Croatia’s plus-five goal difference is all but insurmountable.

So even if the Croats were to lose to Iceland on Tuesday in Rostov-on-Don, we’ll figure them for first place.

The rest is a mess. Besides Iceland (one point) facing a must-win situation, Nigeria (three) needs at least a draw against desperate Argentina in St. Petersburg. If that were to occur, the only way Iceland would topple the Nigerians would be to beat Croatia — good luck — by multiple goals.

Messi and Argentina, two-time champions and 2014 finalists, cannot do it by themselves. Beating Nigeria is the first step. While their match transpires, they’ll be rooting for Croatia to defeat or tie Iceland.

GROUP E

Brazil and Switzerland are tied on points (four). The Brazilians have a slight advantage in goal difference in case they finish even but they also have a tougher matchup: Serbia (three points) on Wednesday in Moscow, while the Swiss play Costa Rica (none) in Nizhny Novgorod.

A Swiss victory and Brazil draw is not out of the question, a scenario that would drop the five-time champions into second.

GROUP F

Germany’s dramatic victory over Sweden set the stage for a nail-biting finish to the group. There is a chance three teams could finish with six points, triggering perhaps layers of tiebreakers.

For that to happen, Germany (three points) would have to defeat South Korea on Wednesday in Kazan and Sweden (three) would have to beat Mexico (six) in Ekaterinburg. The tie-breaking order: goal difference, goals scored, head to head and fair-play conduct (yellow cards, red cards). If all else fails, FIFA will draw lots.

Mexico has been in terrific form and could end much of the suspense by winning again. By doing so, it would probably avoid Brazil in the round of 16 and maybe set up a Germany-Brazil showdown.

GROUP G

We know who is moving on: Both England and Belgium have six points, plus-six goal differences and eight goals scored. So naturally they’ll draw Thursday in Kaliningrad, right?

Both could use a good test before the knockout stage begins. Given the situation, though, some key players are likely to rest ahead of the next stage.

Potential matchups won’t provide much motivation because the Group H teams are so diverse. England and Belgium seem likely to enter as favorites, regardless of the pairings.

GROUP H

With their draw Sunday, Japan and Senegal remain the surprise leaders with four points apiece. Now, they’ve got to take the final step by holding their ground against the pre-tournament group favorites.

While Japan gets to play eliminated Poland (no points) in Volgograd, Senegal faces a massive challenge in Samara against Colombia (three), a 2014 quarterfinalist that got back on track Sunday in emphatic fashion by defeating the Poles. Given the attacking attitudes, this promises to be a crackling match.

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