The attacking midfielder joined from London rivals Chelsea in the summer, on a reportedly large contract. He has since struggled to show his best form, failing to score a single goal so far and not starting any of the last eight Premier League games.
Former club captain Tony Adams recently criticised the decision to sign him at all and said the club are "going nowhere" with such deals, but Luiz says the quality Willian has shown throughout his career will surface again in time.
“Everyone knows the player Willian. And everyone knows Willian’s potential. And he doesn’t have to prove anything to anyone after so many years at the highest level," Luiz told ESPN Brasil, per Goal.
"He’s in a moment which is not so pleasant on the individual level because things are not happening.
“But he’s an experienced, intelligent guy, who knows what he should know, and what he must do every day."
Luiz went on to point to his own career, which has had its share of ups and downs - such as good recent form ending with a red card in the defeat to Wolves during the week - as proof of it being more likely than not that Willian can resurrect his own form and star for the Gunners in future.
"He’s a guy who will get through this, he will get through this moment and he’ll still bring a lot of joy to Arsenal, to this club. Because there’s this turbulence, just as I had in the first few months. It’s not easy, you change clubs, from one rival to another, you have all the cannons facing you. Everything you do people will compare [to what you'd done before].
"My first months weren’t easy, and that’s what I try to pass on to Willian: ‘Calm down, things will work out, things will happen. Just keep working because you’re you, there’s no way to change. You’re a great person and you’re a great player. Calm down. Things are going to happen’."
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