The Brazil international made a surprise switch across the capital on deadline day, joining the Gunners from the Blues in a deal worth a reported £8m
It seems Luiz's departure left the Blues head of medical Paco Biosca in tears, such was the friendship the pair had struck up during their time together at Stamford Bridge.
In a clip captured by Arsenal's media team, the Brazilian was seen telling the Gunners' medical director Gary O'Driscoll: "Paco's amazing. He's crying, he's crying.
"He called me crying.
"I have a great, great relationship with him."