Peru captain Paolo Guerrero scored twice in a win over Saudi Arabia after the temporary lifting of a drug ban means he can play at the World Cup.
"I am very happy to come back with two goals but we have to keep our focus, nobody can take away our concentration", Guerrero told reporters.
"Most likely, we are battling Peru and Australia for second place, and that's why it's important to get a good start, and we have to have fit players", Hareide added.
Coach Age Hareide said he gave the forward a chance to prove his fitness, but Bendtner was unable to show he could play a part at the World Cup, where Denmark have been drawn with Peru, Australia and France in Group C.
They quickly took control and Carrillo fired them in front in the 20th minute, controlling the ball on his chest and scoring with a half-volley after a clearance was headed straight to him.
Former Arsenal striker and cult hero Nicklas Bendtner has been left out of Denmark's 23-man squad for the World Cup.
Peru already led 1-0 when Guerrero followed up to score from close range in the 41st minute after an initial shot was saved.
Guerrero could yet have to complete a 14-month ban imposed by the Swiss-based Court of Arbitration for Sport for his positive test for metabolites of cocaine at a FIFA World Cup qualifying game last October.
Guerrero was initially banned for 12 months by Federation Internationale de Football Association, reduced to six on appeal.
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