Manchester United midfielder Casemiro accepts he is learning on the job by playing centre-back, but says he is happy to help the team out.
The five-time Champions League winner has been used at the heart of the back four by manager Erik ten Hag due to injuries that have ruled out a number of our central defenders in recent weeks.
Jonny Evans, Willy Kambwala, Victor Lindelof, Harry Maguire, Lisandro Martinez and Raphael Varane, plus Luke Shaw, who can also operate in the middle, have all had spells out.
Evans has returned to the line-up and Martinez came off the bench against Newcastle United in midweek.