Relegation-threatened Livorno have sacked Domenico Di Carlo after just 88 days in charge and re-appointed Davide Nicola.
Virgil van Dijk claims he knows nothing of interest from English clubs and is keen to prove himself in the Champions League with Celtic.
The 21-year-old completed his medical on Monday morning and has signed a two-and-a-half-year deal with the Sky Bet League One promotion chasers.
Dicko finished last season at Molineux, scoring once in four outings, but could not prevent the club from dropping out of the Championship.
The former Blackpool and Rotherham loanee failed to find the net in nine appearances for Wigan.