Are Argentina in danger of missing the World Cup? Here's the current state of play in South America

Lionel Messi and Neymar are experiencing very different qualifying campaigns with their countries

With just six rounds of fixtures to go in the South American section for qualification for the 2018 World Cup, every game is now crucial.

The top four teams will qualify for Russia, and the fifth-placed team will advance to the inter-confederation play-offs. Brazil - unbeaten in their last 11 qualifying games - are four points clear at the top, but there is an intriguing chase going on behind them with just five points covering the next five teams.

Among those struggling to keep pace with Brazil are 2014 World Cup runners-up Argentina, who face a nervy four games in order to cement their place in Russia. Here's the state of play and what to look out for...

Crunch time

All eyes will be on Buenos Aires on Thursday evening, as two South American heavyweights clash in a game of huge importance.

Chile, in fourth, take on Argentina, in fifth, and just one point separates them. A win for either team could prove pivotal - but the damage done by a defeat surely outweighs victory. This looks a must-not-lose for both teams, especially with Colombia in sixth having a very winnable home fixture against Bolivia.

Arsenal boss Arsene Wenger declared Alexis Sanchez's ankle in "a terrible state" after a damaging defeat to West Brom, but the forward has taken part in training and seems determined to feature, writing on Instagram: "The only failure is not to try".

El único fracaso Es No intentarlo... ⚽️🇨🇱 A post shared by Alexis Sanchez (@alexis_officia1) on Mar 20, 2017 at 9:56am PDT

We'll know more about how good this latest Brazil team are when they take on Uruguay, while Argentina and Chile will be hoping Paraguay can do them a favour and beat Ecuador.

Argentina's next game, five days after the Chile fixture, is a daunting trip to the high altitude surroundings in Bolivia, which could prove problematic, especially if they get a negative result on Thursday.

Forthcoming fixtures (UK time) Thu 23: Colombia v Bolivia (8.30pm)

Colombia v Bolivia (8.30pm) Thu 23: Paraguay v Ecuador (11pm)

Paraguay v Ecuador (11pm) Thu 23: Uruguay v Brazil (11pm)

Uruguay v Brazil (11pm) Thu 23: Argentina v Chile (11.30pm)

Argentina v Chile (11.30pm) Thu 23: Venezuela v Peru (11.30pm)

Venezuela v Peru (11.30pm) Tue 28: Bolivia v Argentina (9pm)

Bolivia v Argentina (9pm) Tue 28: Honduras v Costa Rica (10pm)

Honduras v Costa Rica (10pm) Tue 28: Ecuador v Colombia (10pm)

Ecuador v Colombia (10pm) Tue 28: Chile v Venezuela (10pm)

Chile v Venezuela (10pm) Tue 28: Brazil v Paraguay (1.45am)

Brazil v Paraguay (1.45am) Tue 28: Peru v Uruguay (3.15am)

What's wrong with Argentina?

Argentina coach Edgardo Bauza says he's imagined Lionel Messi holding the World Cup aloft in Russia - well perhaps the coach has been doing too much daydreaming as Argentina's qualification campaign has been a mess.

Bauza has coached Argentina for four games since replacing Gerardo Martino after the Copa America in the United States, but home defeats to Ecuador and Paraguay and draws against Venezuela and Peru, added to an embarrassing 3-0 defeat to great rivals Brazil, have left one of the world's most iconic teams with questions to answer.

Neymar embraces Lionel Messi after Brazil's win over Argentina in November

A 3-0 home victory over Colombia in their most recent fixture was a welcome boost, but they still remain outside the automatic berths with tricky away trips against Bolivia and Uruguay still to come.

A return of just 14 goals from a side that includes the likes of Messi, Sergio Aguero and Angel Di Maria has drawn criticism, as Bauza has struggled to find a style of play that suits his star men. Of course, there is still plenty of football to be played - but at this stage, Argentina are well off the level set by Brazil.

Bauza has remained defiant, though, telling FIFA.com: "All I'm focusing on is setting up the team to be champions. There's always been rivalry with Chile but we need to boil it down to this one game, which is an important one against a direct rival. The only thing that should be in our minds is that if we beat them, we overtake them. I feel like a winner, I feel like I am going to win."

Argentina's Lionel Messi (middle) is marked by Brazil's Gabriel Jesus

Brilliant Brazil back to their best?

Remember when Brazil lost 7-1 to Germany? That low moment in Brazilian football history seems more than two-and-a-half years ago now as with the introduction of fresh blood, Brazil are back to somewhere near the standard required.

Since taking charge midway through the campaign new boss Tite has overseen six straight victories, which has put them firmly in control of their destiny. The five-time world champions are on course for Russia 2018 and are producing an attacking style of football that will create a buzz in the build-up to next year's tournament.

Brazil's Gabriel Jesus (left) celebrates after scoring against Peru

Gabriel Jesus and Phillippe Coutinho have made a big impact for Tite, especially the Manchester City star, who had direct hand in all three goals on a stunning senior international debut against Ecuador, before scoring three more in the next four matches.

This youthful Brazil side look a real force going forward, with Neymar maturing into crucial attacking figurehead. In the very impressive 3-0 win over Argentina, Neymar netted his 50th international goal, to go with efforts from Coutinho and Paulinho, in a very comfortable win.

Suarez biting back?

"I admitted my mistake, that I had done wrong, as many people make mistakes, something normal in the life of a human being."

Those were Luis Suarez's words after his made his return to the Uruguay side having been banned from international football for 636 days after biting Italy defender Giorgio Chiellini during a World Cup group match in Brazil. He made his comeback in March last year and his performances have suggested he's keen to make up for lost time. His team have won all of their home matches during qualification in convincing fashion, conceding just one goal, and also picked up a 2-2 draw away in Brazil, where Suarez scored.

Luis Suarez celebrates his goal for Uruguay against Colombia

A World Cup without Suarez just wouldn't be the same. He'll be keen on writing the wrongs of his behaviour in Brazil by leading Uruguay to Russia. They are halfway there.

Keep track of all the World Cup Qualifiers on skysports.com and the Sky Sports apps.