It was a transfer made particularly enticing by the fact his contract was set to expire this June, and as a result Spurs could have signed him on a free transfer.
That is now no longer possible, with Djalo's new deal running until the year 2020. To make life even more complicated for Tottenham, Sporting have confirmed via their website that the contract includes a release clause of a huge sum: €45 million.
This is the same figure which exists in the contract of Portugese international midfielder William Carvalho, from which they have been unwilling to budge amid reported interest from Manchester United, cited by The Telegraph among other outlets last year.
For Spurs, the deal effectively ends their chances to sign the highly rated prospect this summer, who has now been shown a huge sign of commitment by his club and the 18-year-old is unlikely to be tempted away.
He would have been signed as a prospect, a player for the future, but with the price to sign him a steep one, Spurs will be better off keeping faith with their current midfielders, and January signing Dele Alli.