Neymar's fitness will be under the microscope on Friday as Brazil try to kickstart their World Cup campaign, anxious to avoid the same fate as a shambolic Argentina and the under-performing Lionel Messi.

Argentina, the 2014 finalists, slumped to a 3-0 defeat by Croatia that ruthlessly exposed the flaws in an ageing team that is over-reliant on Messi.

Messi barely had a shot on target and Argentina failed to recover from a terrible mistake by goalkeeper Willy Caballero that gifted the Croats their first goal and the two-time champions now face an uphill battle to qualify for the knockout phase.

Neymar, Brazil's most important player, was subjected to rough treatment in a 1-1 draw against Switzerland, his first competitive appearance in almost four months, before hobbling out of the Rostov Arena.

The 222-million-euro man then limped out of a training session two days later with a sore right ankle, but Brazil coach Tite has confirmed he will start against Costa Rica in Saint Petersburg.

While Neymar sporadically showed flashes of his genius against Switzerland, he appeared to slow Brazil down at other times rather than keep the ball moving.

But Tite quashed rumours he has told the 26-year-old to play more in the team's best interests.

"Absolutely not. The information you got is not true," Tite responded to a Brazilian journalist. "All of the players have this responsibility of playing for the collective (good) and being individuals."

Thiago Silva will skipper the side as Tite continues his policy of rotating the captaincy, and Neymar's Paris Saint-Germain teammate admitted there is little margin for error.

"It's going to be a very difficult match given (Costa Rica's) loss in the first match, and a draw for us. There's pressure on both sides," Silva said.

"You must keep a cool head to play well and have a good performance."

Brazil's opponents on Friday, surprise 2014 quarter-finalists Costa Rica, were beaten 1-0 by Serbia in their first game in Group E, and another defeat would mean elimination.

History is against Costa Rica: Brazil have won nine of 10 previous meetings with Los Ticos.

However, Bryan Ruiz is hoping his side can become the latest to slow down one of the tournament favourites and keep their adventure going.

"You've seen already there have been plenty of surprises," Ruiz said.

Aleksandar Kolarov's brilliant free-kick got Serbia up and running as they look to reach the last 16 for the first time since becoming an independent nation.

A win over Switzerland in their second game in Kaliningrad would guarantee Serbia a place in the knockout stage, regardless of the outcome of their final group match with Brazil.

"It's very important that we have these three points in the bag, but it's not over, Switzerland will be the hardest match," said Kolarov.

Swiss coach Vladimir Petkovic vowed to keep faith with the rugged approach that frustrated Brazil as they look to apply the brakes on Serbia's Sergej Milinkovic-Savic and Nemanja Matic.

"I will speak with the players and tell them we've had a great match against Brazil but that's not enough. We have to give our best and we want to win the match," Petkovic said.

In Group D, Nigeria must raise their game against Iceland after a 2-0 defeat by Croatia to avoid being dumped out after just two games.

The game carries added significance for Argentina, who will be hoping Nigeria can claim a win to improve their chances of remaining in the tournament.

Nigeria coach Gernot Rohr batted back a question about his job possibly being on the line were the Super Eagles to suffer a similar fate as African rivals Egypt and Morocco.

"We will not lose this game so I do not answer this question. You can ask this question again after the game, but I will tell you we will not lose," Rohr said.