Scans have revealed that our German midfielder damaged the cruciate ligament in his right knee in Wednesday's Worthington Cup semi-final at Chelsea.
The 31-year-old former German international requires surgery and faces a lengthy lay-off.
Steffen suffered exactly the same injury in his left knee ironically against England in the Euro 96 semi-final at Wembley Stadium.
But he was back in time to play a part in Borussia Dortmund's Champions' League triumph the following season and insists he will be back again from this latest setback.
Speaking today, Steffen declared: "I know what is coming, I know what I have to do and that is why I know I will be back.
"It is very disappointing because I believe there are good times ahead for Tottenham. We are playing well and confidence is high.
"What more can I say? I am quite depressed now and it is very diffcult to talk about it suffice to say that I've faced it before and I am not worried about facing it again."
Steffen Freund has vowed to return from the second serious knee injury of his career.