Former Liverpool striker Stan Collymore has urged Chelsea to sell defender David Luiz at the end of the season. The Brazilian, who suffered a torrid time in the 3-1 Champions League quarter-final, first leg defeat to Paris Saint-Germain last week, has been linked with a move to Barcelona by Spanish newspaper Marca on a number of occasions. A source close to Stamford Bridge told [football] direct news that PSG have also expressed an interest, and ex-England international Collymore believes the 26-year-old should depart during the summer transfer window. He said on Twitter: “Bite their hand off at 20 (million pounds).”Utility man Luiz, who has often been deployed as a holding midfielder by manager Jose Mourinho this season, has three years remaining on his lucrative contract in west London. He joined Chelsea from Portugese heavyweights Benfica in 2011, but has found regular first-team opportunities hard to come by under Mourinho and could be tempted to seek a fresh challenge elsewhere. Watch Arsenal v Everton, West Ham v Liverpool on Sunday. 24-hour Sky Sports day pass for only 9.99. No contract.