Tottenham Hotspur fear Jan Vertonghen will be sidelined for eight to 10 weeks after a scan revealed ligament damage to the defender's left ankle, a source close to the club has told ESPN FC.
Vertonghen, 29, has suffered grade two or three damage after turning his ankle in the 4-0 win over West Bromwich Albion on Saturday.
A club source said Spurs are still assessing the results of Monday's scan, and are planning to allow Mauricio Pochettino to update the media at Thursday's prematch news conference, rather than making an announcement.
The Spurs manager has previously been reluctant to put a timeframe on injuries, having been overly-optimistic about the likely to returns of Toby Alderweireld and Erik Lamela this season, but he is expected to say that Vertonghen is unlikely to play until the end of March.
The Belgium international will miss Saturday's match at Manchester City and the visit to Liverpool on Feb. 11, and the injury is a significant blow to Spurs' title hopes, particularly as Vertonghen has looked so comfortable as part of the back three, which Pochettino has used since the turn of the year.
Pochettino must now decide whether to stick with the formation, and replace Vertonghen with Ben Davies or Kevin Wimmer, or revert to a back four with Eric Dier partnering Alderweireld in the heart of defence.
Last season, Vertonghen damaged his knee ligaments against Crystal Palace on Jan. 23 and missed 12 weeks, with Wimmer deputising.
Speaking after the win against West Brom, Pochettino said: "You can see in the game that Ben Davies can play [there] -- we have plenty of players. We do not need another [defender]."
Alderweireld added: "We hope that Jan is not injured for too long. If anybody is injured I think there is a lot of people who can play in his place and bring the level that he brings. We're confident in our squad and people have to step up."