After a disappointing draw against Morocco in their opening match, Brazil arrived under pressure to deliver a stronger performance. They responded with an impressive first-half display led by Matheus Cunha and Vinicius Junior.
Brazil thought they had taken an early lead when Raphinha finished from a Bruno Guimaraes pass, but the goal was ruled out for offside. The breakthrough eventually came midway through the first half when Cunha reacted quickest after Haiti goalkeeper Johny Placide parried a powerful effort from Vinicius. Despite desperate defending on the goal line, the striker forced the ball home.
Cunha struck again soon afterwards. Latching onto a perfectly weighted pass from Vinicius, he powered a finish into the roof of the net to double Brazil's advantage.
Vinicius then capped an outstanding first-half performance by scoring Brazil's third goal. Exploiting space behind Haiti's defence, the Real Madrid forward raced through and calmly slotted past Placide to put the result beyond doubt before the break.
Speaking after the match, Ancelotti explained why he handed Cunha a starting role.
"I think that for this game Matheus Cunha's position was a good one to create problems for the defence," said the Brazil coach. "He also filtered passes very well and moved into position really well. He can be an option."
The Italian also praised Vinicius, who finished with a goal and an assist.
"He came into the World Cup well, in excellent condition. We don't expect it to be Vinicius' World Cup, we expect it to be Brazil's World Cup."
Ancelotti revealed that Brazil adjusted Vinicius' role during the match to make him even more dangerous.
"We moved Vini a little more inside. He is dangerous not only one-on-one, but also when attacking in behind. He scored a goal and provided an assist."
Haiti improved after the interval and nearly reduced the deficit when Ricardo Ade's header forced Alisson Becker into a sharp save. Brazil continued to create chances and even had an Endrick goal ruled out for offside, but the score remained unchanged.
Ancelotti was pleased with the overall display, although he felt his side could have scored more.
"We were much better in the first half, with more effectiveness up front. In the second half we had more control. We had many opportunities, we could have scored more goals. Overall it was a good game."
Brazil now sit level on four points with Morocco and will look to secure their place in the Round of 32 when they face Scotland in their final Group C match in Miami on Wednesday.