Brazil's poor performance in their goalless draw against Costa Rica in their Copa America opener on Monday has dampened the enthusiasm surrounding their new manager and a revamped squad headlined by Vinicius Jr.

After a gritty 1-0 win over England at Wembley and a hard-fought draw 3-3 with Spain at the Bernabeu earlier this year, fans were optimistic that Brazil had turned a corner under Dorival Jr but his side had no answers to Costa Rica's five-man defence in California.

As the clock ticked down and the five-time world champions' frustrations grew, Dorival decided to make his first two substitutions in the 70th minute.

His decision to take Vinicius out of the game came as a huge surprise.

Even Brazil talisman Neymar, who is recovering from a serious knee injury but was at the stadium as a fan, could not hide his dismay.

The broadcast showed his reaction in the stands when the stadium speaker announced the change, exclaiming "Vini?" repeatedly, with his arms open, looking at his friends in disbelief.

Vinicius arrived at the Copa America as a strong contender to win the Ballon d'Or after a hugely successful season with LaLiga winners Real Madrid.

The 23-year-old netted their second goal against Borussia Dortmund in the Champions League final as Real claimed a record-extending 15th European crown.

The jet-heeled forward torments defences and always seems to come to the fore when the pressure is at its highest, scoring 24 goals for his club last season.

He was rarely substituted by Real manager Carlo Ancelotti, who often said Vinicius was at his most dangerous late on in games and gave the forward the freedom to roam across the front line.

Things are different with Brazil.

Vinicius is deployed as more of an orthodox forward wide on the left and has scored only three goals in 31 games for Brazil.

Dorival's decision to take him off on Monday brought back memories of the 2022 World Cup quarter-finals, when then manager Tite also substituted Vinicius early in the second-half against Croatia, a game Brazil ended up losing on penalties.

On Monday, Vinicius struggled to make an impact from the left wing and exited the game without a shot on target.

Dorival said he tried moving Vinicius around before replacing him with 17-year-old forward Endrick.

"We tried with him on the wing and we didn't succeed. Then put him inside and we couldn't find a way through either ... he was very well marked," Dorival said.

"We had to find a solution, I was trying to make a change. We tried various alternatives, several situations were created, but in the end we were unsuccessful with our finishing."

The challenge for Dorival in Brazil's upcoming games will be finding a way to balance their attack without sacrificing his best player.