Arsenal have already agreed a deal (though not officially confirmed, but going by the media reports it is as good as done) for Chelsea goal keeper Petr Cech, and the two London giants could be involved in few more transfer battles this summer.
Jose Mourinho wants to bolster his defence this summer and he is keen to sign the 24-year-old Algerian international.
The Blues have been playing Cesar Azpilicueta as their first choice left-back for the past two seasons. With Filipe Luis being linked with a return to Atletico Madrid, it seems Chelsea are looking to sign a new left-back.
London rivals Arsenal have now joined the race to sign the defender. The Gunners could be lining up a €15m bid when the transfer window reopen next month, but will face tough competition from Chelsea.
La Liga giants Real Madrid could be interested as well, as Rafael Benitez, their new manager knows the player very well, having played him 36 times in Serie A over the course of the past two seasons.