Lionel Messi was fed up and hurting three years ago, on the losing side once again at the Copa America.

"For me, the national team is over. I've done all I can," Messi said after Argentina's penalty-shootout loss to Chile at the 2016 edition in the United States.

Three years later, the five-time world player of the year is back at South America's biggest tournament, the guy Argentina is relying on once again to end its trophy drought in international soccer.

Now 31, Messi is still among the best players in the world. He is coming off another prolific season for Barcelona — 51 goals in 50 matches in all competitions — where he led the Spanish team to a fourth league title in five years.

Trophies at club level and personal awards just keep on coming for Messi. It's on the international stage that he continues to fall short, meaning that for many — especially in Argentina — he still cannot compare to country's other great player, Diego Maradona.

Argentina enters the Copa America in Brazil without a major international trophy at the senior level since 1993. That was the year it won the South American championship for the second straight edition and 14th time overall. Seven years before that, Argentina won the World Cup, mainly thanks to Maradona.

A quarter of a century without a big title is too long for such a soccer-crazy nation and it is weighing heavily on its players. Hence Messi's emotional reaction after the 2016 final, when Argentina slumped a second straight shootout loss to Chile in the final.

When the tournament begins on Friday with Brazil playing Bolivia, the host nation will be the favorite but the absence of Neymar because of an ankle injury should provide Argentina with more optimism.

"We have the best player in the world, we will try to help him so he feels comfortable," Argentina midfielder Rodrigo De Paul said of Messi. "But we are aware that Brazil is the favorite."

Led by interim coach Lionel Scaloni, Argentina has many young players in their first international tournament. With Sergio Aguero, Paulo Dybala and Angel di Maria among the other attackers, the concerns again lie in the defense, where Argentina has been weak for some time.

If Messi can lead an Argentina team in transition to the title — at the home of its greatest soccer rival — all that pain and anguish from previous misses at the Copa America and World Cup will likely disappear in an instant.

Even in a career as stellar as Messi's, it will rank as one of the highlights.

Here is what else to watch out for at the Copa America:

SOUTH AMERICAN STRUGGLES

It would be the ideal time for South American soccer to put on a show at the Copa America and reassert some of its grandeur.

European teams have won the last four World Cups, the biggest streak on record. The club game in Europe, led by the Champions League, has never been so dominant and appealing.

Is South American soccer being left behind?

At the end of 2016, four South Americans players were widely considered the best in their positions: Messi, right back Dani Alves (Brazil), left back Marcelo (Brazil) and Luis Suarez (Uruguay). Other players like Thiago Silva (Brazil), Alexis Sanchez (Chile) and Gonzalo Higuain (Argentina) were coming off impressive seasons. Every match played at the 2016 tournament in the United States included a key player from a top European team.

Former Brazil player Junior, who is a commentator at TV Globo, said those days are over and South American players are lagging behind the Europeans.

"The great players in the region are either nearing their retirement, in trouble or not ready to have a leading role," he said. "This Copa America is important. We need to see either new stars rising or a last great run of the veterans. If not, European domination could advance into the next World Cup cycle."

OUT-OF-FORM STARS

When Junior spoke of players "in trouble," he might have been referring to Alexis Sanchez, the most famous player for defending champion Chile who scored only once for Manchester United in 20 matches this season. He might not even be at Old Trafford next season.

Or maybe James Rodriguez, the Colombia playmaker who is leaving Bayern Munich after a two-year loan spell and doesn't appear to be wanted by Real Madrid.

Or maybe Philippe Coutinho, the Brazil midfielder upon whom Brazil might be depending following Neymar's injury. Coutinho has had a disappointing first full season with Barcelona, where he has been jeered by fans.

TICKETS

Copa America organizers have been worried about ticket sales at the tournament, saying only 65 percent of all tickets have been sold.

However, organizers said the opening match between Brazil and Bolivia in Sao Paulo and Saturday's match between Argentina and Colombia in Salvador are sold out.

More than 1 million tickets have been put on sale, and the target is to sell 70 percent of them, Copa America director of operations Agberto Guimaraes said.

To avoid empty seats, Guimaraes said organizers are in contact with the local government about the possibility to have school children fill some of them.

BRAZIL

Even without Neymar, the hosts are big favorites.

Brazil has won the tournament all four previous times it has hosted the tournament.

Watch out for striker David Neres, who is likely to replace Neymar after an impressive season for Ajax.