Bolton have rebuffed Chelsea's undisclosed offer for striker Nicolas Anelka.
Head coach Avram Grant wants the French international to bolster his attacking options with Didier Drogba on African Nations Cup duty later this month.
Anelka has taken Chelsea's eye after scoring 11 goals this season in a struggling side.
The London club made their first formal bid today, PA Sport understands, but it has been rejected by Bolton.
Former Arsenal striker Anelka signed a new four-year contract earlier this season but his superb form has seen him strongly linked with to a move to a bigger club.
Valued at about £10million, only last week he revealed to a French newspaper that Bolton and Chelsea were in a dialogue about a possible move.
However manager Gary Megson refuted claims a deal was imminent and following the FA Cup defeat by Sheffield United on Saturday he insisted there had been no formal approach for Anelka by any club.
A brief statement on Chelsea's official website, tonight read: 'We can confirm we have made an official offer for the transfer of Nicolas Anelka, which is being discussed with Bolton Wanderers.'
Chelsea are in the hunt for a new striker following the loss of Ivory Coast's Didier Drogba to the African Nations Cup and Andriy Shevchenko through injury.
Chelsea have just one fit striker for tomorrow night's Carling Cup semi-final first leg tie against Everton.
It is understood that negotiations for the transfer of Anelka will continue over the next 24 hours.