Chelsea are still trying to convince Napoli to let Dries Mertens join Stamford Bridge before the end of the transfer window on Friday, sources have told ESPN.

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The Belgian striker wants to sign for the Blues but the discussions between the two clubs are moving slowly, sources added.

Mertens, 32, is out of contract in the summer and Chelsea have offered €7 million to recruit him now. Napoli president Aurelio De Laurentiis rejected the bid and is proving quite difficult to deal with. Chelsea director Marina Granovskaia is leading the pursuit for Mertens and is considering making a better offer of €10m on Friday to secure the signing.

Chelsea have been desperate to recruit a striker this month but have failed so far. The future of Olivier Giroud will also depend of the arrival of Mertens. The London club was ready to let the Frenchman leave as he is not part of Frank Lampard's plans. But the club is now refusing to allow Giroud to leave unless a replacement is signed.

Giroud has agreed to personal terms with three teams -- Inter Milan, Tottenham and Lazio -- and all of them have a deal in place with Chelsea for a loan and an option to buy in the summer.

Yet, the French striker remains at Chelsea as he tries to secure more playing time in the second half of the season, or risk being left out Les Bleus squad for Euro 2020.