The 20-year-old was heavily linked with Tottenham Hotspur.
Tottenham have been heavily linked with the 20-year-old in recent weeks and it was reported via Football Italia on Sunday that the Catalans had turned down an unspecified bid for the Paraguay international.
But in a fresh and somewhat unexpected development, the young striker looks set to join Poyet at Betis after the Uruguayan - who spent three years at Tottenham as a player until 2004 - sold the youngster on the idea of Betis during a number of phonecalls, as reported by Sport.
The report goes on to claim that Spurs delegates were expected to travel to Barcelona last week but scrapped the plan when it was discovered that he was not keen on a switch.
It later suggests that Sanabria - who spent last season with Sporting Gijon, 11 times in 29 Liga outings - was not interested in leaving Spanish football or learning English.
If he joins Betis, it represents quite a coup for Poyet, given how Barcelona were also reportedly interested in bringing him back to Camp Nou following his exit to Roma in 2013.
But his first-team prospects would have been flimsy at Tottenham or Barcelona so that might well have played on his mind also.
Tottenham are expected to complete a deal for Dutch hitman Vincent Janssen within the next 48 hours, according to ESPN.