Brazil thrashed Uruguay to move to the brink of the World Cup finals as Lionel Messi got Argentina's faltering qualification campaign back on track with the only goal to sink Chile.
A superb hat-trick from China-based midfielder Paulinho powered Brazil to a 4-1 drubbing of the Uruguayans in Montevideo to leave the five-time world champions all-but-certain of a place at next year's finals in Russia.
The Brazilians now lead the 10-team round-robin competition by seven points after their latest win.
The top four teams in the standings qualify automatically and with only five rounds remaining, it would take a freakish set of results to deny Brazil.
Uruguay had taken the lead after only nine minutes when Brazil goalkeeper Alisson brought down Paris Saint-Germain striker Edinson Cavani for a penalty.
Cavani got to his feet and drilled the spot-kick beyond the Brazilian goalkeeper to put Uruguay 1-0 up.
But Paulinho produced a thunderbolt 10 minutes later, uncorking a screamer into the top corner from 25 yards to level at 1-1.
The midfielder then stabbed home Philippe Coutinho's shot in the 51st minute to make it 2-1.
Barcelona superstar Neymar added a third with a sublime chip in the 75th minute to effectively settle the contest.
Paulinho completed his hat-trick in injury time, turning in a low cross with his chest to cap a fine display.
Uruguay, who were missing the suspended Luis Suarez, remain in second place in the standings.
"To come here and win by any score is a great result," Brazil coach Tite said afterwards. "Playing in this stadium and beating Uruguay is difficult for anyone."
'A bitter result'
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Uruguay skipper Diego Godin said the final scoreline was not an accurate reflection of the game.
"We trained well, we looked strong," the Atletico Madrid defender said. "It's a bitter result. We had chances. This doesn't reflect the game."
"But this is a wake-up call."
In Buenos Aires, Argentina had entered their clash with Chile desperately needing to take all three points to revive their campaign.
And captain Messi duly delivered when it mattered as Argentina avenged last year's Copa America Centenario final defeat to the Chileans with a 1-0 win.
Messi stroked home his penalty on 16 minutes after veteran Chile defender Jose Fuenzalida brought down Angel Di Maria with a clumsy challenge.
Last year, Messi was left distraught after missing his penalty in the shootout at the Copa America Centenario in New York. But the diminutive maestro made no mistake yesterday, drilling his spot-kick beyond former Barcelona teammate Claudio Bravo to secure a vital three points for the two-time world champions.
Argentina finished the game on the back foot as Chile swarmed forward in search of an equaliser -- a successful rearguard action that delighted coach Edgardo Bauza.
"It was great that we won against a good team, but for me the best thing was the way we fought," Bauza said.
The win leaves Argentina in third place overall in the 10-team qualifying competition with 22 points from 13 games.
But the defeat means two-time reigning South American
champions Chile are still struggling to qualify for Russia.
The Chileans remain outside the automatic qualification places.
Colombia back in hunt
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Colombia, the 2014 World Cup quarter-finalists, boosted their chances of qualification with a 1-0 win over Bolivia in Barranquilla.
Real Madrid star James Rodriguez bundled in the rebound from his own late penalty to claim the points.
Rodriguez rammed home his finish at the second attempt after Bolivia goalkeeper Carlos Lampe had saved the playmaker's spotkick on 83 minutes.
Until Rodriguez's late winner, it looked as if Bolivia had done enough to earn a point, defending in depth and frustrating the hosts at every turn.
But Bolivia's luck ran out when Cristian Coimbra brought down winger Juan Cuadrado with a clumsy challenge to give Rodriguez his chance for glory.
