Mikel Arteta hailed Arsenal's capture of Willian and expects his new signing to "make a real difference" with his versatility and experience.
Arsenal confirmed the arrival of free agent Willian on a three-year deal on Friday, five days on from the Brazil international's departure from Premier League rivals Chelsea.
Predominantly used on the right wing for Chelsea, Willian is also comfortable playing on the left or in a central role and arrives at the Emirates Stadium with an impressive list of honours to his name.
Eyebrows have been raised at the length of the contract awarded to the 32-year-old, but Arteta believes his side's first signing of the close season will prove his worth.
"I believe he's a player that can really make a difference for us," Arteta told the club's official website. "We have been monitoring him for the past few months.
"We had a clear intention to strengthen in attacking midfield and the winger positions and he is a player that gives us a lot of versatility - he can play in three or four different positions.
"He has the experience of everything in the football world but to still have the ambition to come here and contribute to bring the club where it belongs.
"I have been really impressed with all the talks I have had with him and how much he wanted to come."
Willian, handed the number 12 shirt by Arsenal, has been capped 70 times by Brazil since making his debut in 2011 and has appeared in five major international tournaments.
Arsenal director Edu, who previously worked with the Brazil national team, shares Arteta's confidence that his compatriot can be a big hit after crossing the London divide.
"I know him very well, since a long time ago because we've been working together for the Brazilian national team and of course I was following him because he played for another club.
"He has a lot of fantastic attributes as a person, as a football player of course, his character. I'm 100 per cent sure that everybody in the dressing room, the fans, myself and Mikel will enjoy having Willian in our side."