The Argentine has scored 39 times for the Catalan outfit this season, but recent reports have claimed that he is not content with life at the Camp Nou.
As a result, Sanchez believes that a move to the Bernabeu is not out of the question.
"Messi is not feeling valued highly enough by Barcelona with his contract and they must be careful," he told beIN Sports.
"If Barca are careless, I can see Real Madrid signing him."
Sanchez represented Madrid between 1985 and 1992.