Since then, the levels of excitement have continued to swell, with Saul himself stoking the flames with a daily countdown to the big announcement.
Naturally, speculation and debate has surrounded what the "new club" could be, with Manchester United fans particularly excited and optimistic that recent rumours surrounding their interest in the highly-rated midfielder could be proven true.
It would certainly be easy to come to that conclusion; last month reports emerged that Saul to Manchester United was "practically done", and now a little over a week later he is ready to announce a new club.
Adding two and two together from those clues seems to produce an obvious answer: Saul is heading to Old Trafford.
If that is true, it would be a major signing for United, not only for the quality of the player but also the money involved in the post-coronavirus market.
Saul is contracted to Atletico until 2026 and has a release clause of £132m in that deal.
United are hopeful of lowering that price significantly, but it will still likely take a bid of at least £60m to prise the Spain international away from the Wanda Metropolitano, and that in turn could have a knock-on effect on their pursuit of other targets.
Jadon Sancho remains the top target and will cost £70m at the very least, and considering Ed Woodward's warnings that spending will have to be cut back after lockdown, that would not appear to leave much left over for the new centre-back or centre-forward United are after too.
However, it is not the money which makes this deal so unlikely - it is the way in which it has been announced.
The tantalising nature of the post has predictably set tongues wagging, with Manchester United legend Rio Ferdinand among those intently watching for the big reveal at 10am BST Wednesday morning.
So too has Saul's reported Instagram activity - his last four follows have allegedly been Manchester United, David Beckham, Paul Pogba and Juan Mata - all evidence to suggest that a move is actually in the offing.
Saul, or those in charge of his social media and branding, will know exactly what they are doing, though.
The reports of him potentially joining United drew huge interest, and now all eyes will be glued to his social accounts for the announcement at 10am tomorrow.
It could well be to confirm a move to United, but it is difficult to see how a player who has come through the ranks with Atletico and has been at the club for 12 years would reveal his exit in such a way.
Saul was only 13 years old when he joined Atletico, and during his time at the club he played in every Spanish team from the Under-16s up to the senior side, in addition to making almost 300 first-team appearances for Los Rojiblancos.
Now 25, Saul has won two Europa Leagues, the Copa del Rey and reached the Champions League final with Atletico.
In 2017 he signed a new nine-year contract - an almost unprecedented level of commitment in football from both the club and the player himself.
This is a player who loves Atletico Madrid, and the prospect of him prolonging the agony of their fans with a drawn-out exit announcement, thus alienating himself to the support who have adored him for so long, appears to be very slim.
Not to mention that Saul still has to play for Atletico for the rest of the 2019-20 campaign; just before lockdown he helped them into the Champions League quarter-finals, dethroning holders Liverpool in the process, while Diego Simeone's side remain locked in a top-four battle in La Liga too.
Should Wednesday's announcement indeed be confirmation that he is leaving, Saul would be opening himself up to months of being booed, jeered and abused by his own fans.
There is a precedent of sorts for that in Atletico's recent history, though; Antoine Griezmann's 'The Decision' announcement, in which he confirmed he would be staying at Atletico rather than leaving for Barcelona, did not go down well with either club's supporters. Griezmann then joined Barca a year later anyway.
Griezmann would no doubt be the first to warn Saul off a similar mistake, and the feeling of betrayal would be even worse should a player who has come through the Atletico ranks go down such a convoluted path again.
Atletico Madrid themselves, not to mention Simeone, would surely not allow it.
So what could the "new club" announcement be if not a move to Manchester United?
Saul has ensured that thousands will be watching and waiting to see what his "new club" is, which means that it may well be a commercial or sponsorship deal.
There has been speculation that it will be a new e-sports team, or with everything going on in the world at the moment it could be a charitable venture.
There are plenty of hints to suggest that it could be a transfer too, but Manchester United fans would do well not to get too excited by the possibility of them having a new top-class player on their books by this time tomorrow. body check tags ::