Chelsea and Arsenal face each other an the Premier League next month and Willian is not planning to take it easy on his Brazilian teammate.
Luiz sealed a surprise switch from Chelsea to Arsenal last summer in an £8m deal.
He had two spells with Chelsea with Willian present during both periods that has seen them win the Champions League, Europa League and FA Cup together.
And despite also being good pals from the national team, Willian admits there’s no loyalties when it comes to facing one another.
Willian warned Luiz, who is not stranger to a nutmeg, to keep his legs closed when coming up against him.
“I’ve faced him a few times, he for Chelsea, me for Shakhtar, me for Chelsea, he for PSG,” he told Globo Esporte.
“Now it’s he for Arsenal. He’s a brother that I have, we met at the age of eight.
“But on the pitch… there’s no way. If I have to nutmeg him, I will.”