Defending Copa America champions Brazil may have the smoothest path to this year's final but the hottest competition could be in the other half of the quarterfinals, where archrivals Argentina and Uruguay could meet in the semis.
The quarterfinals were finalized on Monday after the last two group matches.
Argentina beat Bolivia 4-1 and ensured it finished atop Group A, setting up a game against Ecuador.
Ecuador has yet to win after a loss and three draws, including 1-1 with Brazil on Sunday. Ecuador is third in South American World Cup qualifiers.
"We have the utmost respect for Ecuador, they have proven to be a good, young and dynamic team that will surely give us a war,” Argentina coach Lionel Scaloni said.
If Lionel Messi's lineup beats Ecuador, coached by Argentine Gustavo Alfaro, its faces Uruguay or Colombia. That matchup has produced some great encounters recently, including Colombia's 2-0 win in the Round of 16 at the 2014 World Cup in Brazil.
On Monday, Uruguay set up the latest match by defeating Paraguay 1-0. The only goal came from the spot by veteran Edinson Cavani.
"We grew as the Copa advanced," Uruguay coach Oscar Tabarez said. "We needed to win and we needed to improve our game; both things are happening."
Uruguay has 15 Copa America titles, the most recent in 2011. Argentina has 14 but none since 1993.
Brazil is aiming for a 10th South American championship.
The most immediate challenge for Neymar's Brazil will be Chile's aging team.
Chile's only win so far was against Bolivia but it may be reinforced by striker Alexis Sanchez, who missed the group stage due to injury.
A win against Chile on Friday will put Brazil in the semifinals against Peru or Paraguay. Both teams recently lost to the Selecao without offering much resistance.
On June 8, shortly before the Copa America, Brazil won at Paraguay 2-0 in World Cup qualifying. Days later, Brazil crushed Peru 4-0 in the group stage of the Copa America.
Brazil also has the advantage of having all of its potential knockout matches in Rio, close to its Granja Comary training ground in Teresopolis.
However, Neymar criticized Nilton Santos Stadium - the venue for their quarterfinal and potential semifinal – on Monday for a second time. The stadium field has been heavily criticized for lacking enough grass since the start of the tournament, including by Neymar after the Peru win.
The final is on July 10 at Maracana.
