Chelsea were believed to be rebuffed in their first attempt to sign Mertens from Napoli, who are reluctant to lose the player.
But the Blues will submit another bid as they try and reinforce their attack before the transfer deadline tomorrow night, according to The Telegraph.
Frank Lampard is adamant that Chelsea can't rely on Tammy Abraham for all their goals and has challenged reserve striker Michy Batshuayi to show what he can do.
PSG striker Edinson Cavani looked certain to join Atletico Madrid but the latest reports suggest the two clubs have failed to come to an agreement.
But Chelsea aren't giving up their search and Napoli are thought to be bracing themselves for one last assault for Mertens.
It's was reported that the Belgian could be signed for as little as £6m as his contract expires in the summer.
Chelsea aren't opposed to letting Giroud leave but any sanctioning of the deal may depend on whether they bring a forward in.
How are the Premier League's top sides doing in the January transfer window?
