Mikel Arteta believes Willian is the player who can drive Arsenal towards a push for more silverware and a top-four finish.
Willian, 32, signed a three-year deal with Arsenal in August after leaving Chelsea as a free agent.
The playmaker – who joined Chelsea from Shakhtar Donetsk in 2013 – scored 37 goals and provided 33 assists in 234 Premier League appearances for the Blues.
Arteta thinks the Brazil international will provide Arsenal's squad with much-needed balance, and he has no concerns over Willian's age or ambition.
"With all the conversations I've had with him, the thing that stands out is his ambition that he wants to be the man who can drive this team forward," Arteta told a news conference.
"Another thing with him is he is always available. Last season at Chelsea, you can see the amount of games he has played.
"I am not concerned at all. We need some balance in this squad. We have some really young talent.
"We need some experienced players who can just put the shirt on and start performing. If he is able to perform at that level for another three years, I think he has a great chance of achieving that but time will tell."
Arteta retired from playing in 2016 at the age of 34, with the former Everton and Arsenal midfielder having struggled with injuries in the final stages of his career, though he insisted Willian's situation is in no way comparable.
"He is much fitter [than I was]. Don't compare him with me, I am a bad example!" Arteta joked.
"We need to know our context. For us to sign that type of player at 20 or 21 at the moment is impossible. We need to adapt here.
"We need some players that can hit the ground straight away and others we need to develop them, and they need top players around them because that will increase their performance and their value."
While Willian will add further guile and experience to Arsenal's attack, Arteta may have a headache in regards to the other end of the pitch, with Bernd Leno and Emiliano Martinez – who impressed at the end of last season – fighting for a spot in goal.
Arteta, whose side start their league campaign against Fulham on Saturday, is not concerned over either player being unhappy playing second fiddle, though reports on Friday suggested Martinez may be nearing a move to Aston Villa.
"The positive thing is we have a goalkeeper in Emiliano who for 10 years has been so patient, he has made some difficult choices to earn the right where he is at the moment," Arteta said.
"Since I joined he has been superb, his performance increased dramatically and he helped us to win titles. For me it's a really good problem to have.
"They both need to know their roles. At the end of the day the other one has to support the one who is playing 100 per cent. If you cannot do that you cannot be part of a top squad and you should not be here."