Luis Suarez is out for Uruguay's first match, according to reports Friday.
The striker has resumed training since having knee surgery in May, but Uruguay coach Oscar Tabarez said he was still unsure whether the Liverpool star would make it onto the pitch for Uruguay's match vs. Costa Rica on Saturday.
The Uruguayans would start with forwards Edinson Cavani and veteran Diego Forlan, he said, if Suarez hadn't fully recovered.
"We are increasing [Suarez's] pace of recovery and up until now there have been no glitches," Tabarez said Friday.
"We still have one day to go. We don't want to jump the gun. We have prepared not to have him, but it would be wonderful to have him. We have to be very careful."
The 2010 semifinalists start their Group D campaign in Fortaleza before taking on England and Italy.
Tabarez said Suarez, who had arthroscopic surgery on his knee on May 22, had rejoined full training a day earlier, after practicing on the sidelines since arriving at their training base near Belo Horizonte.
On Friday, the 27-year-old Liverpool striker joined his teammates in their sleeveless training shirts during a casual practice session at Fortaleza's Arena Castelao.
With files from The Associated Press