Manchester United defensive midfielder will miss four local matches after seeing a straight red during the Southampton at OldTrafford.
Casemiro was dismissed after 34 minutes of the 0-0 draw for a tackle on Carlos Alcaraz, but Ten Hag has not ruled out an appeal.
The midfielder’s sending off followed a VAR review, with referee Anthony Taylor overturning his initial decision to show a yellow card for a tackle that hit the top of the ball first before going into Southampton forward Alcaraz’s leg.
Raphael Varane insists Manchester United will find a way to plug the gap left by Casemiro’s four-match ban, but admits they are unhappy about referee Anthony Taylor’s decision to send off the Brazilian in the goalless draw with Southampton.
Taylor initially gave Casemiro a yellow card for his challenge on Carlos Alcaraz just after the hour mark at Old Trafford on Sunday, but upgraded it to a red after being advised by VAR official Andre Marriner to review the decision on the pitch-side monitor.
Despite having a man advantage for almost an hour and managing 17 shots, Southampton were unable to capitalise and remain bottom of the Premier League.
Casemiro will now be banned for Sunday’s FA Cup quarter-final against Fulham and the Premier League games against Newcastle, Brentford and Everton, meaning he will have missed United’s last 16 domestic games through suspension.