After losing four of their last five qualifiers with a series of poor performances, the record five-time World Cup winners are fifth in the standings on 10 points, ahead of Venezuela on goal difference in sixth. Only the top six are guaranteed a berth at the 2026 finals.
Paraguay and Bolivia are one point behind and another slip-up by Brazil could leave them out of the qualification places and at risk of missing out on the World Cup for the first time in their history.
Manager Dorival Jr, who was appointed in January after the team spent a year under two caretaker coaches as the Brazilian FA tried and failed to lure Italian Carlo Ancelotti from Real Madrid, has won only two competitive games.
Following a lacklustre Copa America campaign, when they were knocked out in the quarter-finals by Uruguay, Brazil snatched a narrow home win over Ecuador last month.
Yet they came crashing back to earth days later with another poor performance, losing 1-0 to a Paraguay side who had only scored once in their previous seven qualifiers.
The inconsistency that has plagued Brazil since they let coach Tite go following a penalty shootout defeat to Croatia in the Qatar World Cup quarter-finals has continued with the side winning only four of their last 14 games.
Dorival was forced to make five changes to his initial squad for the games against Chile in Santiago on Thursday and against Peru in Brasilia on Tuesday, after goalkeeper Alisson, defenders Bremer, Eder Militao and Guilherme Arana, and forward Vinicius Jr all suffered injuries.
On Wednesday, the coach made the surprise announcement that Botafogo forward Igor Jesus would start up-front against Chile on his first call-up for the national team, leaving Real Madrid teenager Endrick on the bench.
"What I see is that Igor's moment is very interesting, Endrick is still getting to know his new club, he's arriving at the biggest club in world football with a lot of competition," Dorival told reporters.
The 23-year-old Jesus has been a stand-out talent for the Brazilian league leaders and Copa Libertadores semi-finalists since signing for Botafogo from Emirati club Shabab Al-Ahli in July, scoring seven goals in 19 games.
"I think that Igor's own experience and the moment he's living is a little different," Dorival added. "Maybe it's important to have players with this profile for a game of this magnitude and at this time.
"Sometimes we can't replicate on the pitch everything that we do in training, but on Tuesday we had another training session that filled us with great expectation. Maybe this is the moment to find the balance we want."
Chile are ninth in South America's World Cup qualifying standings on five points, two points ahead of last-placed Peru.
Brazil team to face Chile: Ederson; Danilo, Marquinhos, Gabriel Magalhaes, Abner; Andre, Lucas Paqueta; Savinho, Raphinha, Rodrygo, Igor Jesus.