Brazil, who last missed out on a World Cup quarter-final place in 1990, never really found their rhythm.
Norway looked confident right from the start, with Sander Berge getting a goal within three minutes that was ruled offside and Orjan Nyland saving a weak spot-kick from Bruno Guimaraes - a choice of penalty taker that had baffled many fans, given his relative lack of experience.
That decision was based on a statistical analysis, said Ancelotti.
"According to that, Neymar was the best person to take the penalty, and then Raphinha, and then Bruno," he said. "So we chose him as we felt he was the best on the field." Neither Neymar nor Raphinha were in the starting team.
The pace -- possibly weighed down by an oppressively humid day -- stayed slow on both sides, neither seemed keen to press, and chances were missed.
Neymar was sent on to huge cheers from the crowd at the second-half hydration break and the pace picked up but Brazil were left to rue their relaxed start as talisman striker Erling Haaland scored two late goals for Norway. A penalty by Neymar in stoppage time was not enough to save Brazil.
"At the beginning it seemed to me we were a controlled team, we were creating opportunities," Ancelotti told reporters. "It was difficult to put on too much pressure because Norway was locking its defence, applying too much is a risk."
The team would continue to do their job and "look for new ideas," Ancelotti said, acknowledging a lack of quality in midfield.
"We need some young talent, we need some high-level players coming into Brazilian football.
"I think we did a solid job, but that’s football for you, that’s sports. Sometimes you have to taste defeat," he added.