Thiago Silva has admitted that he is expecting a tough test from Croatia next Thursday after Brazil recorded victory in their final warm-up match ahead of the World Cup.

Fred's goal earned the hosts a 1-0 win over Serbia on Friday night, but Silva believes that there can be no room for complacency as they prepare for the opening game of the tournament.

"Today we had a lot difficulty in the first half and this served to show us how much more difficult it will be against Croatia," the Paris Saint-Germain defender told reporters.

"Croatia should play the same way [as Serbia]. We must be very careful, learn our lessons from this game and believe that our opening match will be very complicated."

Brazil will also meet Cameroon and Mexico in Group A.