Davies sustained a hamstring injury in Saturday's dramatic 3-3 Premier League draw at Southampton and subsequently pulled out of national team duty with Wales this week.
A scan has confirmed the severity of the defender's hamstring injury and he could be sidelined for up to six weeks, Planet Sport understands.
That would see Davies out until the start of May and potentially absent for six crucial fixtures next month with Spurs set to face top-four rivals Brighton, Newcastle, Manchester United and Liverpool during April.
While uncertainty remains over the future of head coach Antonio Conte, Davies joins a growing list of players on the treatment table.
Captain Hugo Lloris (knee), Ryan Sessegnon (hamstring), Yves Bissouma (ankle) and Rodrigo Bentancur (knee) were all unavailable for the St Mary's clash.
Richarlison is another Tottenham player set for a spell on the sidelines after he sustained a muscle problem last weekend that forced him off in the opening minutes against Southampton.
It could deny Richarlison a Goodison Park return on April 3 with Spurs set to resume their league campaign following the international break with a trip to Everton.
A small group of first-team players continue to work at Hotspur Way but not under the watchful eye of Conte.
Conte is still in Italy after he flew back following Saturday's six-goal thriller on the south coast, a trip which was already planned and has been the case during international breaks throughout his time at the club.
First-team coach Ryan Mason and assistant Cristian Stellini have worked with Barcelona loanee Clement Lenglet, Japhet Tanganga, Arnaut Danjuma and Lucas Moura, as well as back-up goalkeepers Brandon Austin and Alfie Whiteman since they returned to training on Tuesday.