(CNN) -- Argentina striker Sergio Aguero may have scored two goals as a second-half substitute on his Manchester City debut, but the club's manager Roberto Mancini maintained the 23-year-old has yet to regain his full fitness. City opened their English Premier League campaign on Monday with a 4-0 victory over top-flight newcomers Swansea City, with Aguero netting a brace after replacing Nigel de Jong on 60 minutes. Italian coach Mancini said Aguero, who joined City from Atletico Madrid for a club-record fee in July, was short of peak fitness because of his appearances for Argentina at the recent Copa America.
@highlight
Roberto Mancini has said Manchester City's Sergio Aguero is not yet 100%
@highlight
The Argentina scored two goals as a second-half substitute on his debut against Swansea
@highlight
City defeated the newly-promoted side 4-0 with goals from Aguero, Dzeko and Silva
I think he needs to recover after the @placeholder because I don't think he's 100%."