The 20-year-old Italian, who had been in line to make his first-team debut for the club at Aston Villa on Saturday, damaged his right knee is training last week, and there were fears that he could be missing for a month.
However, manager Alan Pardew is keeping his fingers crossed that he could return to training within days.
Capital calling: Santon has travelled to London to have fluid drained from his knee
He said: 'He has gone to London today and will have his knee drained of a little bit of fluid that's on it, and then we are hoping that he will train.
Waiting game: Newcastle boss Alan Pardew
'If that doesn't work, probably at some stage, we will have to look at some keyhole surgery in there to make sure that this fluid doesn't appear again.'
Santon's absence is a blow for Pardew, who signed him from Inter Milan to replace Jose Enrique following the Spaniard's move to Liverpool.
Utility man Ryan Taylor has been filling in at left-back, but it remains to be seen whether he gets a rest for Tuesday night's Carling Cup third round trip to Nottingham Forest.
Frenchman Hatem Ben Arfa, who has not played a competitive game for the club in almost a year, will figure at the City ground, but Alan Smith will miss out with a hamstring injury and Dan Gosling is a doubt with a groin problem.
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