Diego Costa scores a wonder goal as Chelsea beat Fenerbahce before falling to Besiktas in pre-season tournament

Blues forward continues his fine pre-season with another superb strike

Diego Costa excelled for Chelsea yet again (Getty Images)

Chelsea's new £32m striker Diego Costa has continued his rich vein of form in a Blues shirt with another wonder goal as Jose Mourinho's men continue their pre-season in Istanbul.

The former Atletico Madrid man started both games, against Fenerbahce and Besiktas, as Chelsea won one and lost the other.

Costa scored a brilliant goal to send Mourinho's side on their way during the clash with Fenerbahce, beating four defenders before firing the ball into the net.

Chelsea will be under increased scrutiny this season after a trophy-less campaign last time around.

Andre Schurrle, Oscar, Willian and Ramires all made their first appearances of the summer after returning from the World Cup as the Blues got back to winning ways after a disappointing 3-0 defeat to Werder Bremen last week.

In the later kick-off, Ersan Gulum grabbed the decisive goal for Besiktas as the Turkish side won the mini-tournament at the Sukru Saracoglu Stadium.

Former Blues hitman Demba Ba featured for the victors but was denied twice by Petr Cech in the Chelsea net.

Didier Drogba, who returned to action against Bremen, came closest for the Blues, seeing a decent free-kick knocked away by goalkeeper Cenk Gonen.

Mourinho won't be too disheartened by his side's failure to lift the trophy but the battle between Cech and Thibaut Courtois appears to have swung in the Czech Republican's favour after his younger rival started the heavy defeat to Bremen.