Luiz Felipe Scolari has already called up the European-based players for the Selecao's friendly with South Africa on March 5 in Johannesburg.
On the list are three forwards—Bernard, Neymar and Hulk—but no one to act as the side's spearhead.
Fluminense striker Fred, who scored five goals during the Confederations Cup, is the main reason Scolari has delayed in calling up Brazil-based players, as reported by Brazilian outlet Terra's Andre Naddeo.
But it remains unclear whether Fred will be fit in time, having missed the best part of the last six months with various physical complaints.
On Feb. 7, he suffered an injury to his right thigh before the Fla-Flu classico against Flamengo. He returned to training on Tuesday but didn't risk his right leg in shooting exercises.
The continued mystery surrounding Fred gives fresh hope to rival Leandro Damiao. The striker has swapped Internacional for Santos during the Brazilian offseason after a poor run of form and his own unlucky spell with injuries.
The game against South Africa will be the final international before Felipao must name his 23-man World Cup squad on May 7.
Fred's injury record is well documented and lengthy. Should he not make the final cut in June, Scolari will need to assess what other options are available.
Big Phil has shown in his selections what kind of player he likes to occupy the No. 9 shirt: a target man, physically strong and powerful in the air who can hold the line, drawing in the playmakers around him and linking them to the attack.
It explains his preference to have a reference in attack, like Fred or Jo. Damiao also fits the bill, having played the majority of his international career under predecessor Mano Menezes.
But Damiao has not worn the yellow of Brazil since June last year when he came on for Fred in the 2-2 draw between England and Brazil at the Maracana just days before the Confederations Cup.
Santos could end up being a good fit for the 24-year-old. Since being shorn of Paulo Henrique Ganso and Neymar, the Vila Belmiro outfit are looking for a high-profile player to propel the team forward.
His knack for scoring in international tournaments is proven. He bagged six during Brazil's 2012 Olympic campaign, and he would have been part of last year's Confederations Cup had he not had to pull out through injury.
Jo took his place and grabbed his chance with both hands. He scored in the Selecao's first two games against Japan and Mexico, but his finishing and lack of consistency in front of goal can let him down.
Should Leando Damiao be recalled to the Brazil side?
If Fred does miss the tournament, Brazil suddenly look lightweight up top, their lack of options in a vital position exposed.
It is at times like this that one may think Scolari would love to be able to turn to Diego Costa. His form is excellent and is one of the most in-demand properties in the European transfer market.
Now that he is lost, Atletico Mineiro's Jo, who scored the winner for his club in their Copa Libertadores opener against Zamora of Venezuela, and Damiao are competing for one spot.
And the latter, who at one time was considered the long-term successor to the likes of Ronaldo and Adriano, has a prime chance to get his career back on track.
Scolari admitted on Tuesday he is worried about Fred's physical form, as reported by Brazilian newspaper Globo Esporte. The former Lyon forward has yet to play in 2014.
Last year, he scored just six goals for Fluminense in all competitions. By way of comparison, he netted 10 for the Selecao.
Missing the South Africa game would be a blow to the player and the coaching staff, but it opens the door to those trying to score a late invite to Brazil's World Cup quest.
If he can perform consistently for Santos, Damiao may be arriving at the front door right on time.
Stats via Transfermarkt unless otherwise specified.