"Following preliminary assessments, we can confirm that Harry Kane has damaged ligaments in his left ankle, sustained during Sunday's match," a club statement read.
"He will continue to be monitored by our medical staff as he commences rehabilitation and is expected to return to training in early March."
Following preliminary assessments, we can confirm that @HKane has damaged ligaments in his left ankle, sustained during Sunday's match.— Tottenham Hotspur (@SpursOfficial) January 15, 2019
He will continue to be monitored by our medical staff as he commences rehabilitation and is expected to return to training in early March. pic.twitter.com/Ot3doPa4K6
After the United match, Spurs boss Mauricio Pochettino admitted he was "worried" about his star striker, who was forced off near the end of the game at Wembley.
And Pochettino's fears have now been realised, as Kane appears set to miss a significant amount of the rest of the season.
Spurs' defeat to United on Sunday was a significant blow to their title hopes with the club now in third place, nine points behind table-topping Liverpool.
And Kane's absence will be an arguably bigger hit to Pochettino's side, with the 25-year-old in the midst of another prolific campaign and Heung-min Son currently on international duty at the Asian Cup with South Korea.
Kane is the co-leader in Premier League goals this season with 14, tied with Pierre-Emerick Aubameyang and Mohamed Salah atop the league's scoring chart.
Overall, Kane has 20 goals in 31 appearances in all competitions for Spurs this season.
Kane is also likely to miss both legs of Tottenham's Champions League last-16 tie against Borussia Dortmund.
The first leg of the tie will take place February 13 at Wembley, with the return leg set for March 5 at Signal Iduna Park in Dortmund.