Argentina lifted last year's Copa America title with a 1-0 win in the final over Brazil at the Maracana, their first major title since 1993. The Lionel Messi-led side built on that success earlier this month by claiming a 3-0 victory over Italy in Finalissima.
The two South American sides went unbeaten in World Cup qualifying, although Brazil finished six points ahead of Argentina in the qualifying table.
"I see Argentina and Brazil well above all the other national teams," Luis Enrique told a news conference on Saturday. "Well above the rest."
Meanwhile, Enrique's Spain side have been unconvincing in this month's international break. The 2010 World Cup winners head into Sunday's Nations League game against the Czech Republic looking for only their second win in the tournament in a 1-0 victory at Switzerland on Thursday.
Spain drew their opening Group A2 games, a 1-1 result against Portugal followed by a 2-2 draw at the Czech Republic.
"If some expect us to win all of the games and do so by thrashing our opponents, they know nothing of modern football," Enrique said. "Look at France, the  World Cup Champions and  Nations League winners."
France are bottom of Group A1 after taking two points from their opening three Nations League games.
Ansu, 19, has not played for Spain since October 2020 due to injuries and hamstring problems, and he made just 14 appearances for Barcelona last season.
"I have no doubt that he will return to his level," Enrique said. "He is a unique player in terms of his rapport with goal.
"We were the first to call him up because we were aware of that. We can't be in a hurry. He's had a very difficult year and we must mark the necessary steps that I believe are the best for him. We are not going to take any risks."
Ansu's Barca teammate Gavi has started all three of Spain's opening Nations League games.
The teenage midfielder beat the record previously held by Ansu by becoming Spain's youngest ever goalscorer at 17 years and 304 days after netting against the Czech Republic on Sunday.
Enrique praised Gavi's talent but said the highly-rated midfielder, who is talks with Barca over a new contract, still has a lot to learn.
"Gavi has a lot to improve on and off the pitch," he said.