We want at least one message from somebody in Quito tonight. Or at least someone who has been there.

You can get in touch with us tonight by tweeting us at #bbcfootball or on text at 81111 (UK Only).

Tim Vickery
BBC Sport South American football expert

Image source, Getty Images

Quito is one of the last places Argentina would choose to play a game when they need to go looking for a result.

At 2,850 metres above sea level, the lack of oxygen in the air makes a real difference. Even some Ecuadorians feel it. Manchester United's Antonio Valencia, who misses tonight's game through suspension, confesses that nowadays he finds it very hard to play in the city where his professional career began. The idea is to run as little as possible - favouring a cautious approach and making it hard to chase the game.

Argentina will have to climb a mountain, both literally and metaphorically.

Radamel Falcao and James Rodriguez both start for Colombia, as does Spurs' new signing Davinson Sanchez.

Colombia are through if they win.

Tim Vickery
BBC Sport South American football expert

Argentina, it must be said, have suffered a significant stroke of ill fortune.

Last year, Bolivia held Chile to a 0-0 draw and beat Peru 2-0. But for the last few minutes of both games they brought on an ineligible player (Paraguayan-born centre-back Nelson Cabrera had been living in Bolivia for three years - long enough to gain citizenship - but Fifa regulations demand a five-year period of residence). Bolivia were stripped of the points they had won, and both games were awarded 3-0 to their opponents.

Without those extra points and goals, both Chile and Peru would be below Argentina in the table. Instead, both are ahead.

Brazil are the only side to have secured a qualifying place in South America.

Peru are hosting fourth-placed Colombia and should they draw, Argentina would be eliminated if they did not win.

Chile, who are third, go to already-qualified Brazil, while Uruguay, who are all-but assured of their place in Russia because of their vastly superior goal difference, need just a draw at home to already-eliminated Bolivia to guarantee qualification.

On Friday night, USA beat surprise package Panama 4-0 to move into third and within touching distance of automatic qualification.

They travel to bottom of the table Trinidad and Tobago knowing victory will seal their spot.

Panama now look destined for a play-off match against Australia to land a World Cup place for the first time in their history.

Honduras, whose match in Costa Rica was put back a day because of Hurricane Nate, also remain in the mix. They could still seal an automatic berth though it would need them to beat group winners Mexico and for both USA and Panama to lose their final games.

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Brazil are the only team to have definitely qualified from South America, with Ecuador, Bolivia and Venezuela the only teams already out.

It's a proper end-of-season showdown...

Tim Vickery
BBC Sport South American football expert

Image source, Getty Images

Argentina have had great days, and managed to reach three finals in three years: the World Cup in 2014, the Copa America the following year and the extra, Centenary Copa in 2016 - all of them lost. But they have become increasingly dependent on flashes of individual brilliance, mainly, of course, from Messi.

In this campaign the dependence on the 30-year-old Barcelona forward has become overwhelming. Of the 17 rounds, he has missed eight - in which Argentina managed just seven points.

He announced his retirement from international football immediately after that third final defeat in July last year, but quickly had a rethink. It is just as well. The three subsequent wins Argentina have enjoyed were almost exclusively down to him. It would hardly be surprising if there are times when he regrets his decision not to retire.

Image source, Getty Images

Manchester City forward Sergio Aguero has returned to training 11 days after he suffered a rib injury in a car crash in Amsterdam.

The 29-year-old striker had been expected to be out for several weeks, but resumed light training on Tuesday.

City say the Argentina international will "build up his fitness in the coming days as he edges towards a first team return".

Aguero is one goal shy of Eric Brook's all-time City record of 177 goals.

Image source, Getty Images

The top four sides qualify automatically. Argentina are sixth.

Argentina can qualify with a win, a draw or even a defeat, but it massively depends on other results. Anything other than a win leaves them skating on thin ice.

Beaten finalists at the 2014 World Cup, Argentina are level on both points (25) and goal difference (+1) with fifth-placed Peru, who are ahead on goals scored.

So tight is the group that four points separate Uruguay in second (28) and Paraguay (24) in seventh and a win for Argentina could see them qualify automatically.

Manchester United winger/full-back Antonio Valencia is banned for Ecuador, and ex-West Ham man Enner Valenica is only on th ebench.

Lionel Messi starts for Argentina, obviously. But there's no Paulo Dybala, Sergio Aguero or Gonzalo Higuain...

All games kick-off at 00:30 BST. Get the kettle on.

Brazil v Chile

Ecuador v Argentina

Paraguay v Venezuela

Peru v Colombia

Uruguay v Bolivia

This is how they stand in the South American qualifying group.

Brazil are already guaranteed of their place in Russia, with the teams coming second, third and fourth after tonight's games set to join them. The fifth-placed team will have a two-legged play-off with New Zealand and those nations sixth and below will be out.

Image source, .

Image source, .

And so it comes to this.

Argentina go into their final World Cup qualifier on the brink of failing to reach the finals for the first time in 48 years.

Image source, Getty Images

Winners in 1978 and 1986. With one of the finest players to ever play the game in their ranks.

Can they really miss out?