River Plate's Copa Libertadores hopes already look doomed. How did it happen?

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It is, of course, not possible to win the Copa Libertadores in the group phase. But it is possible to lose it. Ask Buenos Aires giants River Plate. This Wednesday they host Fluminense of Brazil, the team which (joint with Racing of Argentina) have the best record so far of any team in this year's competition. And it is almost certainly the case that anything but a victory will mean that, with a game still to spare, River Plate will be eliminated.

This would have a huge effect on this year's competition. The Libertadores is in grave danger of becoming an exclusive preserve of Brazil. The last four winners have been Brazilian, the last three finals have been all-Brazilian affairs. River Plate are possibly the best chance of ending the monopoly. They won the title in 2018, were seconds away from retaining it in 2019 and came agonisingly close to reaching the final in 2020. Their recently remodelled stadium has the biggest capacity in South America, and, now coached by Martin Demichelis, they sit comfortably at the top of the Argentine first division.

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And yet they lie at the bottom of their Libertadores group and will need to dig deep to save themselves. How, then, have they got themselves into so much trouble in the continental competition? Partly the order of their fixtures has been unkind. In the four rounds played so far River have already fulfilled all three of their away games. More specifically, theirs is a dangerous group. True, Sporting Cristal of Peru are unlikely to make progress. Ten years have gone by since a Peruvian side made it to the knockout phase. But also there are Fluminense, whose free flowing football has led to many -- including Demichelis and fellow Argentine coach Jorge Sampaoli labelling them as the best team in South America.

And there is also The Strongest from Bolivia, who play their games at the extreme altitude of La Paz. Some 3,600 metres above sea level, it is simply impossible for unacclimatised opponents to play their normal game in the rarefied air. The presence of The Strongest always made this group intriguing. If the Bolivians were to make use of home advantage and win all their matches in La Paz -- which now looks probable -- then the margin for error for the favourites would be reduced.

And it is River who have ended up in problems. Last time out they dropped points away to Sporting Cristal, needing a late goal to rescue a draw. And their visit to Rio a month ago was an unmitigated disaster. Against Fluminense in early May River went down 5-1 -- the heaviest defeat they have ever suffered in the entire history of the Libertadores. And this is the team they must beat on Wednesday. Demichelis said last week that his team is suffering from what he termed "jet stress" -- too many trips to too many pressure matches.

At least his team are now at home this week and in the last round -- and the time has come to see how much he learned from the mauling his team took in the Maracana. The 5-1 is one of those games when the scoreline hides much of the story of the match. For 55 minutes River were probably the better side, controlling most of the action and preventing Fluminense from hitting their passing rhythm. The problem came when, slightly against the run of play, River went 2-1 down ten minutes into the second half. Demichelis went chasing the game -- and forgot one of the key lessons of the contemporary Libertadores.

The financial advantage of the Brazilians is now big, and apparent in the depth of the squads, meaning that like a cagey boxer the wise opponent needs to defend himself at all times. Demichelis took off a centre-back and improvised a strange last line of three, with Leandro Gonzalez Pirez flanked by two full-backs. What started as foolhardy became downright foolish soon afterwards when, perhaps a little harshly, Gonzalez Pirez was sent off. River were left with no effective defence, and Fluminense kept walking through them. In the return game, then, Demichelis will surely take a balanced approach to the need for victory. Morale has been boosted by the return to fitness of two important defenders -- Emmanuel Mammana and the Chilean Paulo Diaz.

He will also have noted that Fluminense have suddenly run into a poor spell. They beat Red Bull Bragantino 2-1 on Sunday, but before that had gone five games without scoring a goal, suffering from a few injuries and perhaps some "jet stress" of their own. But this is not a make or break game for the Brazilians. Just a point at home to Sporting Cristal in the final round would be enough to get them safely over the line.

The pressure, then, is all on River Plate. The final of the Copa Libertadores is not until early November. But for the Buenos Aires giants it comes on Wednesday.