West Ham have completed the club-record signing of Felipe Anderson from Lazio on a four-year deal.
Sky Sports News understands West Ham will pay an initial club-record £35m to Lazio with the deal potentially rising to £42m with performance-based add-ons.
The Brazilian passed his medical with the club on Saturday before agreeing personal terms.
"I feel really happy and fulfilled to join West Ham United," Anderson told the club's official website.
"West Ham is a club with a lot of tradition, lots of great players have played here, like Bobby Moore, Carlos Tevez and Di Canio.
"They were great players and idols here, and I'm aiming big, who knows, maybe I could hit their heights and be a legend here too. I'm really happy to be here. It's a dream come true.
"I want to thank the owner, David Sullivan, because he made a big effort to bring me here. I know how difficult it was, so I have to thank him a lot, and I hope I can repay his faith in me on the pitch with goals and winning games."
He becomes new manager Manuel Pellegrini's seventh signing of the summer following the arrivals of Andriy Yarmolenko, Jack Wilshere, Ryan Fredericks, Lukasz Fabianski, Fabian Balbuena and Issa Diop.
Anderson, capped once by Brazil, joined Lazio from Santos in 2013 and has since scored 34 goals in 177 appearances.
Sky sources understand West Ham are open to letting Michail Antonio leave the club following the arrival of Anderson.
It is understood Crystal Palace are interested in signing Antonio and are considering making a bid of £15m for the 28-year-old winger.