Sanchez struggled for minutes last season and is one of the defenders Spurs are open to offers for this summer.
Villarreal, PSV Eindhoven, Galatasaray and Spartak Moscow have all been linked with an interest in the Colombian defender in the ongoing transfer window.
Sanchez has been studying the offers on his table as he mulls over his next career move ahead of the new season.
And according to Italian outlet Tutto Mercato, the defender is leaning towards selecting Betis as his next destination.
The club from Seville are interested in getting their hands on him and have made a proposal to the centre-back.
A decision is yet to be made but it has been claimed that Betis are emerging as the favourites to sign him.
Sanchez is expected to make his final decision on his next club in the next week.
Once the defender makes up his mind, Betis will look to open negotiations with Spurs for his transfer.