Boulahrouz played just for Premier League games in 2007

The 25-year-old only joined the Blues in a �7m deal from Hamburg a year ago.

But he has fallen out of favour with boss Jose Mourinho and was not included in the club's pre-season preparations on tour in the United States.

Boulahrouz's move to the Uefa Cup holders could help increase the probability of Brazilian right-back Daniel Alves coming the other way.

Chelsea have put in a reported �13m offer for Alves which has yet to be accepted by the Andalucian club.

Dutch international Boulahrouz made 23 appearances for Chelsea and was expected to provide cover across the backline.

However, he played just six matches after the turn of the year as his relationship with Mourinho became increasingly strained and the manager opted to play midfielders Michael Essien, Geremi and Lassana Diarra in defence.

The FA Cup and Carling Cup holders paved the way for his departure by bringing in Tal Ben Haim from Bolton and bringing Glen Johnson back from a loan deal at Portsmouth.

PSV Eindhoven centre-back Alex is also expected to move to Stamford Bridge before the transfer window closes.