Montevideo: Uruguay stayed firmly on Brazil's shoulder with a 2-1 defeat of Ecuador at Montevideo's Estadio Centenario.
The Uruguayans took the lead on 12 minutes when former Liverpool defender Sebastian Coates bundled in a corner from close range for his first international goal.
Espanyol striker Felipe Caicedo then rounded off a sweeping Ecuador counter-attack to equalise just before half-time.
But Uruguay responded immediately, Diego Rolan stabbing home a low finish on the stroke of half-time to restore the home side's lead.
Injury scare for Bravo
Elsewhere, Copa America Centenario champions Chile had captain and goalkeeper Claudio Bravo to thank for a hard-earned point in a 0-0 draw against Colombia in Barranquilla.
The Chileans, missing injured Arsenal star Alexis Sanchez, needed two superb saves from Bravo to keep Colombia at bay in a gritty game played in sweltering conditions.
Bravo's display was tempered by an injury which forced the Manchester City goalkeeper off the field midway through the second half.
The stopper produced two fine blocks to deny Oscar Murillo and Miguel Borja as Colombia were struggled to break the deadlock.
Colombia's Argentinian coach Jose Pekerman bemoaned a lack of precision in front of goal but was buoyed by the return of talismanic striker Radamel Falcao, who was introduced as a half-time substitute.
"We tried everything and we had chances but we lacked precision," Pekerman said.
"But the most important fact of the game was the return of Falcao."
In other games, Paraguay suffered a 4-1 mauling against Peru in Asuncion to derail their qualification campaign.
Paraguay took an early lead through Cristian Riveros after nine minutes but Peru hit back with second-half goals from Christian Ramos, Edison Flores, Christian Cueva and an Edgar Benitez own goal to run out convincing winners.
Paraguay coach Francisco Arce attempted to put a positive spin on his team's loss.
"We're still in the race to qualify," Arce said. "We don't think we're dead, we just need to pick ourselves up and get on with it," he added.
Paraguay, who are two points outside the qualifying positions, face Bolivia away in their next game.
Venezuela scored their first win of the qualifiers with a 5-0 thrashing at home to Bolivia, with Josef Martinez scoring a hat-trick.
Meanwhile, Neymar scored his 50th international goal as Brazil thrashed Argentina 3-0 to tighten their grip on South America's 2018 World Cup qualification campaign and leave their arch-rivals struggling to reach the finals.
Argentina are outside of the qualifying places. But Messi insisted that the two time World Cup winners could still get through to the Russia finals.
Neymar's landmark strike was sandwiched by a spectacular effort from Liverpool's Philippe Coutinho and a second-half finish from China-based midfielder Paulinho.
Brazil have now won five straight qualifying games under new coach Tite, who took over after Dunga was sacked in June because of Brazil's failure to get out of the Copa America Centenario group stage.
Brazil now have 24 points from 11 games, one clear of second-placed Uruguay who have 23 points.
The Brazilians are six points clear of third-placed Colombia and seven points clear of Ecuador and Chile, who are level on 17 points after 11 games.
Argentina languishing outside the qualifying places in sixth with 16 points.
The two-time world champions -- who have taken just two points from their past four qualifiers -- now face a crucial game at home to Colombia next Tuesday which they must win to avoid falling further off the pace.
"We're down but we're still alive," Argentina captain Messi said. "We have to forget the situation we're in and start thinking about Colombia. If we get a result against Colombia it will make things look a lot different."
Argentina manager Edgardo Bauza admitted he had not expected to lose so heavily.
"It's a hard defeat. I did not think we would lose 3-0, I thought it would be an even game," Bauza said. "But when they got their second it was all over."