Brazil leads CONMEBOL in goals scored (38) and fewest goals conceded (11) and are deservedly back at the World Cup to try to help the country forget last tournament's embarrassing 7-1 defeat to Germany in the semifinals.
Chile, who have won two Copa Americas in a row, are Argentina's biggest threat to qualification.
Back in South America, Brazil, the only team to have played in every World Cup since the first tournament was held in Uruguay in 1930, have already qualified for Russian Federation, 10 points clear at the top with 38 points, while Uruguay (28) need just a draw from their final game against Bolivia to advance.
The eyes of the football world will turn to Quito's Estadio Olimpico Atahualpa to see if the once unthinkable prospect of a World Cup without Messi is to become a stunning reality.
It seems unthinkable, but there is very real chance Lionel Messi will not be at next summer's World Cup in Russian Federation.
The show's producer Daniel Grinban told Argentinean newspaper La Nacion: "I proposed that after Noel Gallagher, who leaves at 7pm, we will televise the game of Argentina and then play U2".
While Argentina are riding a four-game winless streak, Ecuador have lost their past five qualifying matches. With qualification secure, Brazil have taken the foot off the pedal, drawing with both Colombia and Bolivia.
A draw will do if Brazil beat Chile by more than one goal and if Argentina draw and Paraguay fail to win.
The match was played at La Bombonera, home of Boca Juniors, and only a win would be enough to put Argentina through.
The home venue of Quito is at high altitude, and Argentina have suffered there in the past, with little oxygen to sustain an empowered display.
"The team that hauled itself to the World Cup final three years ago was heavily reliant on the inspiration of Messi and the grit of Javier Mascherano".
With 10 teams in the frame, a total of 18 rounds are contested before the top four go through automatically and the fifth head into a very winnable two-legged knockout tie against New Zealand. Peru also have a chance even if they draw or lose. A win will guarantee them a play-off berth and possibly a direct place, depending on how Peru and Chile fare. Therefore, winning against Ecuador is imperative if they want to keep themselves alive.
The report, however, claimed that Messi is "happy with his life in Barcelona" as the 30-year-old Argentine feels "wanted" at the club.