Arsenal have agreed an £8m deal with Chelsea to sign defender David Luiz on a two-year contract.
The 32-year-old Brazil centre-back, who signed a new two-year Chelsea deal in May, will have a medical at Arsenal on Thursday.
On Tuesday, Arsenal sold defender Laurent Koscielny to French side Bordeaux for a fee of up to 5m euros (£4.6m).
They are also set to sign Celtic left-back Kieran Tierney for £25m.
Luiz has spent six and a half years at Chelsea during two spells and has made 160 Premier League appearances, scoring 11 goals.
His departure, if confirmed, comes five weeks after Frank Lampard returned to Stamford Bridge to manage his former club.