The report claims Spurs have held preliminary negotiations with the Spanish club over the teenager, who has attracted interest from Arsenal and was dubbed the 'next Cristiano Ronaldo' after breaking into the Betis team aged 16.
Now 18, the winger is highly-rated by his club, who remain adamant he will not be sold unless a huge bid is made.
Club president Miguel Guillen has admitted he will consider a massive offer for Vadillo, but he doesn't want to see the teenager leave the club.
"The club's intention is that Vadillo shall stay at Betis," Guillen is quoted as saying by The Metro.
"For us to allow our young prodigy to depart, there would have to be a very strong financial benefit for the club.
"Vadillo has a great future in front of him, and we are very excited thinking about what he is going to bring to us during this coming season."
The 18-year-old has a £17.3m release clause in his contract, and reportedly began English lessons two years ago at the request of his agent.
And the report claims Spurs will only make their move official if Gareth Bale departs for Real Madrid. They remain desperate to keep Bale at White Hart Lane, but want to get their potential replacement lined up in the event that he does join Madrid.
As a result, they've reportedly opened discussions with Vadillo and scouted him as Betis played Premier League side Fulham at Craven Cottage earlier this week.
Spurs have been watching him for much of the summer, including at the recent European under-19 Championship, but Arsenal have also been strongly linked in recent days.
Gunners boss Arsene Wenger is on the lookout for new signings, but the priority remains a striker at the Emirates Stadium which could allow Spurs to steal a march on their north London rivals in their pursuit of Vadillo.