Without the striker, Uruguay were beaten 2-0 by fellow South Americans Colombia on Saturday night.
"It's true it's not been an easy week, but we're not looking for excuses: they deserved to win," Pereira told FIFA.com. "We knew that Colombia are great on the ball, which is why we tried to press them high.
"We were doing it well until that wonder goal came, which changed everything. After the break we went out looking for the equaliser but then they scored a second, which hit us hard."
Colombia's reward for defeating Uruguay is a quarter-final clash with hosts Brazil.