Julio Cesar points out that in Edinson Cavani, Diego Forlan and Luis Suarez, the Uruguayans have no shortage of firepower.
"They are very strong in attack and can decide a game on their own," the shot-stopper said.
"I know them all well and we shall have to beware. The tiniest thing can decide a match," added Cesar, who faces the prospect of playing second tier English football next season after being relegated with Queens Park Rangers.
Brazil have started their tournament strongly under 2002 FIFA World Cup handler Luiz Felipe Scolari, waltzing through their group with wins over Japan, Mexico and Italy.
Uruguay had to regroup after losing their first match against world champions Spain, who will face Italy in the other semi-final.
"Nobody is favourite. They will be confident as they won the Copa America in 2011," said Julio Cesar.
The four semi-finalists have won 12 FIFA World Cups between them - a record five for Brazil, four for Italy, two for the Uruguayans, including a 1950 success at the Maracana over Brazil, and one for Spain.