The move for a new centre-back is less pressured than the one for a striker, as after 14 months of failing to replace Fernando Llorente and heaping pressure on Harry Kane to play almost every minute, Spurs needed to make that deal for a forward happen.
Mourinho's frustration behind the scenes was growing louder until the breakthrough was finally made for Vinicius.
It's a different scenario when it comes to a new central defender.
The belief within Tottenham is that while they now have at least two top players in every position, the left-sided centre-back role is the one missing piece of the puzzle since the departure of Jan Vertonghen.
Eric Dier can play on that side and has a big admirer in Mourinho, but his fellow senior centre-backs Toby Alderweireld and Davinson Sanchez are far less comfortable there.
The versatile Japhet Tanganga, who earned his first England U21 international call-up this week, can play there, although it's not as natural for him as he is on the right, while left-back Ben Davies can do a job there.
Those options are why Mourinho will not be crestfallen if a new defender cannot be secured by the end of Monday as he can operate in the months ahead with those available choices.
It's also why Tottenham will try to sign a new centre-back who can play on the left before the deadline but only if they can secure the right deal for the squad upgrade they require, rather than spending desperately.
Inter Milan's Milan Skriniar is the club's top choice, but the problem lies in a £13million difference in valuation.
The Serie A side want £45million for the 25-year-old Slovakian but Spurs want a deal closer to £32million with add-ons for the defender, who is very keen on the move.
There has been plenty of posturing from the Italian outfit with their sporting director and head coach Antonio Conte both saying that Skriniar is not for sale, but the latter crucially conceded that the club do need money to fund their own signings.
It's with that in mind that Spurs are expected to return with a new approach late in the window in the hope that Inter compromise in order to push on their own transfer dealings.