The 30-year-old midfielder is set to sign a four-year contract at Old Trafford, with the option of a further year.
Casemiro’s arrival remains subject to the finalising of personal terms, UK visa requirements and a medical.
The Brazil international is nevertheless set to become Erik ten Hag’s fourth signing of the summer, following the additions of Tyrell Malacia, Christian Eriksen and Lisandro Martinez.
The signing of Casemiro means that a move for priority midfield target Frenkie de Jong is now considered highly unlikely this summer.
Casemiro will be among the top earners at Old Trafford once he joins up with Ten Hag’s squad but the terms of his contract are understood to be heavily performance-related.
While United have dismissed suggestions that he will double his Madrid wages, his earnings will be significantly higher if he helps United qualify for and return to the Champions League.
Ten Hag and other figures at United are said to be impressed by Casemiro’s desire to join the challenge of returning United to their former glories.
After winning five Champions Leagues and three La Liga titles during his nine years at Madrid, Casemiro is said to want to test himself in a new environment in the Premier League.
United have endured a miserable start to the season under Ten Hag, losing both of their opening Premier League fixtures against Brighton and Hove Albion and Brentford, leaving them bottom of the table.
Ten Hag is keen to add yet more reinforcements to his squad before the transfer window closes on 1 September, with a central midfielder, forward, right-back and back-up goalkeeper all targeted.
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