Japan and Qatar's participation in the Copa America may have raised eyebrows in some quarters but the two Asian nations have already proved they didn't turn up in Brazil just to make up the numbers.

Qatar began their Group B campaign by fighting back from 2-0 down to draw 2-2 with Paraguay before a late Duvan Zapata goal denied them a point against Colombia in their next match.

And while a youthful and inexperienced Japan side was taught a harsh lesson in clinical finishing by Chile in a 4-0 defeat, they were then on the wrong end of two controversial VAR decisions in their 2-2 draw with Uruguay.

Both sides may only have one point from two group games so far but they know that victory in their final pool encounters will likely see them into the knock-out rounds.

"We want to be protagonists on the pitch, our players have the quality to do that," said Qatar's Spanish coach Felix Sanchez.

"We're a team that never gives up," he added about the Asian champions.

On Sunday, Qatar face a disjointed and underwhelming Argentina for whom Lionel Messi has been unable to spark into life.

And he knows that a victory over Qatar, which Argentina almost certainly need to avoid being knocked out of the competition, is anything but a foregone conclusion.

"You don't win matches any more just by pulling on the jersey," warned the Barcelona star, who turns 32 on Monday.

Having paid for their wastefulness in front of goal and naivety at the back against Chile, Japan coach Hajime Moriyasu rang the changes ahead of their clash with Uruguay.

"They showed a lot of courage to play the game," Moriyasu said of his players, lauding their "defiant spirit" against a "top" team.

Having thrashed 10-man Ecuador 4-0 in their opener, Uruguay had to come from behind twice to snatch the draw with Japan.

Barcelona striker Luis Suarez, who equalized the first time from the controversially awarded penalty, insisted the 15-time Copa winners had not underestimated their Asian opponents.

"We knew the result against Chile the other day was unreliable," he said.

Japan came to the tournament with a squad made up mostly of under-23 players likely to be available next year for the Tokyo Olympics.

When Moriyasu announced his 23-man squad last month, 17 of the players were uncapped.

Two friendlies and two Copa America matches later, and nine of those have since made their debut.

But despite fielding such inexperienced line-ups, Japan have impressed with their speed and industry, as well as a willingness to attack.

While many fans may have regarded the two Asian invitees as amongst the weakest sides in the tournament, both have proved they are no push-overs.

But not everyone has welcomed them with open arms.

"I've never seen a European championships where they've invited a South American team," complained Paraguay's Argentine coach Eduardo Berizzo.

"It could sound unpleasant to say it now that we've played Qatar, but I truly believe that the Copa America should be played between American teams, all integrated in one tournament: CONCACAF and CONMEBOL."

CONMEBOL is the South American governing football federation that organizes the Copa America, while CONCACAF groups countries from North and Central America, and the Caribbean.

The CONCACAF Gold Cup, the Copa America equivalent, is actually taking place at the same time.

Invitees have been a feature of the Copa America since it adopted its current 12-team format in 1993.

While the invitees have mostly been from the Americas -- Mexico have played 10 times, Costa Rica five times and the United States four times -- CONMEBOL had branched out once before when Japan were invited to the 1999 tournament.

This was the first time there had been two invitees from outside the Americas and that policy will continue with the next edition for which Australia and Qatar have been invited to take part.

So far, Mexico have come the closest of the guests to winning the Copa, reaching the final in 1993 and 2001.