Lionel Messi has said Argentina will have to play better than ever and must not rest on their laurels if they are to win a second straight Copa América.

The 2022 World Cup champions begin their Copa América title defence against Canada on Thursday in Atlanta, Georgia. They will also face Peru and Chile in Group A.

"Today, we can say that we are the best because we are the world champions. But that does not make us believe that we are going to win this Copa América by walking," Messi said.

"It is going to be very level, all the teams are complicated. Ecuador has a generation of very good youngsters, who know well what they want, they are intense with the ball, they are clear about what they do and they are physically strong. And like them, you also have Colombia, Uruguay, not to mention Brazil. That's why I say it will be even and our team is aware that we are going to have to continue doing the same and more to win again."

Argentina beat Brazil 1-0 at the Maracana stadium to win the Copa América three years ago, the country's first major title in 28 years.

The Albiceleste have since been in spectacular form, lifting the 2022 World Cup and winning five of their six World Cup qualifiers.

Meanwhile, Argentina's longtime rivals Brazil go into the Copa América under new coach Dorival Junior but without their men's all-time leading scorer Neymar, who is injured.

They lost on penalties to Croatia in the quarterfinals of the World Cup and have won just two of their World Cup qualifiers.

"It [Neymar's absence] is a shame, but they have a million players," Messi said. "Brazil always has plenty of players because they are continually different. They have a very strong, very competitive team. Brazil is like Argentina: it's a candidate and wants to win the Copa América."

Messi, 36, said he plans to enjoy the Copa América that will be staged in the United States and is not thinking about his future.

"I value all those moments [with the squad] very much because I know that there is less and less time left until everything is over and that in some way I am going to miss all of that," the Inter Miami forward said. "The truth is that it was very difficult for me at first to take the step and leave European football to come here [United States], but once I was here I adapted very quickly and live day to day and think in the moment. Today I feel that I am still fine, that I can continue competing, I continue training, I continue taking care of myself just as I always did, or even more, and I live for the moments. For now I don't think about the future."

Messi's Inter Miami coach Gerardo "Tata" Martino does not know if the Copa América will be the player's last for Argentina.

"You see Messi play and you don't sense the end is near, even though perhaps the calendar indicates otherwise," Martino said. "But I think what we have is more of an expression of wish than an analysis for something we really know. I don't know and I hope he enjoys it as he has been enjoying it until now, and then he will decide."

Martino, who is Argentinian, said he believes his country has a great chance of lifting the Copa but added there are other teams that are hungry and capable.

"Unlike other Copa Américas, there are several teams besides Argentina and Brazil that are very good, that have a lot of potential and are willing to fight for it," Martino said. "It seems to me that it will be a very attractive competition. As for Argentina, having fulfilled that aim [to win 2022 World Cup] frees the footballers [from the pressure] and they begin to express themselves at their best ... you find it hard to believe that they could lose a game."