Newcastle United have given European champions Chelsea permission to hold transfer talks with 27-year-old Senegal striker Demba Ba.
"Chelsea have made an official offer for Demba Ba which has triggered the release clause in the player's contract," Newcastle said on their website (www.nufc.co.uk) on Wednesday.
"The club have given the player permission to speak to Chelsea and therefore he will not be included in the squad for tonight's (league) game against Everton."
Newcastle, who are sixth from bottom in the table, did not give details of the release clause but media reports suggest it is around $11.38 million.
Ba has been a mainstay in attack for the north-east club since joining from West Ham United on a free transfer in June 2011.
The striker, who previously had spells with Rouen, Mouscron and Hoffenheim, needed eight games to score his first Newcastle goal but he ended his drought in style with a hat-trick in a 3-1 victory over Blackburn Rovers.
Ba finished the 2011-12 campaign as the club's top league scorer with 16 goals including another hat-trick against Stoke City.
He has continued his free-scoring ways this season, bagging 13 league goals to lie joint second in the overall chart behind Manchester United's Robin van Persie (16).
Chelsea are desperate for backup in attack for Spanish international Fernando Torres who is the London team's most-used outfield player this season.
Options up front have been limited following the exits of Didier Drogba and Salomon Kalou in the close season and the decision to allow Romelu Lukaku to join Premier League rivals West Bromwich Albion on loan.
England forward Daniel Sturridge has joined Liverpool following an injury-interrupted season with the Stamford Bridge club.
Chelsea can go back up to third in the league if they win at home to neighbours Queens Park Rangers later on Wednesday.