BELO HORIZONTE: After missing three matches with an injury, Lionel Messi is back in the lineup for Argentina in its crucial World Cup qualifier against Brazil.

But there's bad news for Copa America champion Chile: Arsenal star Alexis Sanchez is out of Thursday's match at Colombia with a leg injury.

Injuries and suspensions could play a key role as South America's top teams chase places at the 2018 World Cup in Russia.

Argentina is happy to have Messi back after three lackluster matches — which ended with two draws and a loss. Brazil has meanwhile won its first four games under new coach Tite and will be looking to turn the page on Thursday when it returns to the Mineirao stadium in Belo Horizonte where it was crushed 7-1 by Germany in the 2014 World Cup semifinals.

Brazil leads the qualifying group with 21 points from 10 games, one ahead of Uruguay, four ahead of Colombia and Ecuador, and five up on Argentina and Chile.

After beating Ecuador, Colombia, Bolivia and Venezuela, Argentina will give Tite his biggest challenge yet — containing Barcelona star Messi in a game that renews one of the biggest rivalries in world soccer.

"He (Messi) is extremely intelligent and has a great finishing skill, so we have to do double marking on him whenever we can," Brazil midfielder Renato Augusto said. "We have to close the gaps for all Argentina players, and we have to remove Messi's passing angle whenever he has the ball."

Argentina, which lost the World Cup final two years ago to Germany, is coming off 2-2 draws against Venezuela and Peru, and a 1-0 loss to Paraguay.

Back in September, Messi scored in a 1-0 victory over Uruguay in the only match he's played under Argentina's new coach Edgardo Bauza. And the timing of his return couldn't be better.

"We are happy that Messi is back. We know how much he can give and it would be great to win here," midfielder Lucas Biglia said. "Brazil is the ideal rival to get us on track."

Under former coaches Dunga and Argentina's Gerardo Martino, Brazil and Argentina drew 1-1 in Buenos Aires in their first 2018 qualifier.

The top four teams qualify automatically for the World Cup. The fifth-place team advances to an intercontinental playoff.

Here is a look at other teams in action this week:

Uruguay

Second-place Uruguay will face two extra problems against Ecuador in Montevideo: defender Alvaro Pereira and striker Edinson Cavani are both suspended.

The team also has concerns off the pitch. On Monday, the players wore shirts without sponsors' names because of a controversy over image rights. In the news conferences given by players, banners with sponsors were also banned.

"We are trying to reclaim our rights that we understand are ours — and legitimate," Uruguay captain Diego Godin said. "It is the tool we are using to try to help our football and our football players."

Fortunately for Uruguay, the visitors have their own problems.

Coach Gustavo Quinteros will be missing 10 players, with Antonio Valencia, Jefferson Montero, Pedro Quinonez, Matias Oyola and Angel Mena all out because of injuries. Enner Valencia, Luis Caicedo, Leonel Ramírez and Arturo Mina are suspended, while Marcos Caicedo could not travel because of legal issues.

Colombia

An injury that has ruled out Chile's star forward Alexis Sanchez should make life easier for Colombia in its home game at Barranquilla.

Chile's soccer federation said Tuesday that Sanchez will not travel to the game after picking up a leg muscle injury in training. The setback comes after Chile was awarded two extra points following a FIFA ruling that said Bolivia had used an ineligible player in a 0-0 draw.

The 3-0 victory awarded to the Copa America champions meant they have 16 points, just one less than Colombia, but still only in fifth place.

"We have to worry about getting back to our level and not about other things," Chile goalkeeper Claudio Bravo said. "We have to start with the idea that we are out of the World Cup."

The biggest concern for Colombia is about who will lead the attack.

Coach Jose Pekerman has to pick between Miguel Angel Borja and Radamel Falcao. The first is one of the top scorers in South America at the moment, and the second is returning to the team.

Elsewhere, bottom of the group Venezuela hosts fellow struggler Bolivia and Paraguay plays Peru.