And that question could make all the difference between who makes the trip next year and who stays at home.
A victory guarantees Chile the two-time defending South American champions its third straight World Cup berth.
A bad omen is that Argentina began their qualifying campaign with a shock 2-0 home loss to Ecuador two years ago when they were coached by Argentine Gustavo Quinteros. Even an Argentina tie would pull them ahead of Chile if Chile loses to Brazil by more than one goal. Turkey is out of contention after it lost against Iceland 3-0 on Friday, but many nations have everything to play for in their last games.
As for the rest, no one has a clearer path to Russian Federation than Uruguay, who lie second on 28 points. A draw would be good enough for a playoff spot if Argentina wins, and there is a victor in the Peru-Colombia match.
Uruguay are all but qualified.
Argentina have beaten Ecuador only once in a World Cup qualifier in Quito, where the high altitude makes life hard for visiting teams.
Lionel Messi's Argentina slumped to a goalless draw last week against Peru, leaving them in serious danger of not being in Russian Federation next summer. That leaves five teams with varying prospects: Chile (26), Colombia (26), Peru (25), Argentina (25), and Paraguay (24).
Kourtney Kardashian's Ex Scott Disick Kisses Sofia Richie After Father Criticizes Romance
The 19-year-old model is dating Scott Disick , and the 24-year-old model is in a relationship with Kourtney Kardashian . Explaining the situation to a friend, she went on to say, "I can't have fun after seeing those pics".
Finally we reach Lionel Messi and Argentina, now in sixth place in the CONMEBOL standings.
Argentina can simplify the equation for their nervous fans, however, if they manage to take all three points in Quito when the action kicks off at 6:30pm local time (2330 GMT). If not, they will have to face the lottery of the play-offs.
Marcos Rojo, Ramiro Funes Mori and Fernando Gago are out as well due to injury.
Lying a place and a point behind Argentina, Paraguay play host to Venezuela knowing that they will, in all likelihood, have to win to go through. Victory against Ecuador would be enough to secure at least a play-off place. A draw could also yield a playoff for Argentina. La Albirroja will be without the suspended Richard Ortiz.
It seems unthinkable, but there is very real chance Lionel Messi will not be at next summer's World Cup in Russian Federation.
Chile have been poor in the qualifying campaign, and are on the brink of elimination heading into their final game. And that was after Messi had one of his better games for the country. Los Cafeteros are in for sure with a win. "Throughout the game, we had a marked advantage against them but we could not break through". "All we're thinking about is picking up points in Brazil".