Rafael da Silva will join French club Lyon from Manchester United on a four-year contract for an undisclosed fee.
The 25-year-old right-back, who has two Brazil caps, moved to United along with his twin brother Fabio from Fluminense in 2008.
However, he had fallen out of favour at the club under Louis van Gaal, starting just six league games last season.
"I want to thank Manchester United fans for all the love during those eight years," Rafael tweeted.
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He was left out of United's squad for their pre-season tour of the United States, before Torino right-back Matteo Darmian joined the Old Trafford club.
Rafael will join the Ligue 1 runners-up having made 170 appearances for Manchester United, scoring five goals.
He won three Premier League titles, the Club World Cup and the League Cup during his seven years at United.
Rafael's brother Fabio has already left United, having joined Cardiff City in January 2014.
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