North London club have watched Brazilian born star.
Arsenal have watched Atletico Madrid striker Diego Costa, according to The Daily Telegraph.
Costa’s brilliant start to the season, which has seen him score 21 goals in as many games, has alerted interest in his situation.
But the Gunners remain doubtful about landing the Brazilian-born Spanish striker in January because they are reluctant to meet his £32m release clause, and the North London outfit are yet to bid for Costa.
But the club are aware that the 25-year-old is one of the few leading strikers in Europe who will be available in the winter transfer window.
The Gunners are still seeking another striker but Wenger is aware that he will struggle to add genuine quality in the New Year without paying an inflated price.