Fabio Vieira has joined Arsenal from Porto on a long-term contract for a fee believed to be £34.2m.
The 22-year-old midfielder, who is a Porto academy product, has made 54 appearances for the Primeira Liga club and helped the Portuguese side to league titles in 2020 and 2022.
Last season Vieira scored six goals and made 14 assists during Porto's league campaign.
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Arsenal boss Mikel Arteta said: ”I am very excited that we have identified and signed such a special talent.
"Fabio is a very creative player that will bring high quality and versatility to our attacking play.
"We welcome Fabio and his family to our club and are looking forward to starting work with him ahead of the new season.”
“We’re so pleased to have completed the signing of Fabio from FC Porto," Technical director Edu said.
"Fabio is a player with special qualities who is comfortable with the ball in the final third of the pitch. We are all looking forward to working with him and enjoying his future contribution to Arsenal.
"We will now continue to work hard and are looking forward to finishing this transfer window as strongly possible.”
Vieira will wear the number 21 shirt for the Gunners which has previously been worn by Calum Chambers, Lukasz Fabianski, Mart Poom, Jermaine Pennant and Tomas Danilevicius.
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