The Swede linked up for the home match against Crystal Palace on Sunday, and didn't look too downbeat at the time.
But the knee injury would prove to be more serious than it initially seemed, and on Wednesday Tottenham confirmed that Kulusevski had undergone surgery for a patella injury.
And at Thursday's press conference, coach Ange Postecoglou gave a gloomy prognosis for when the 25-year-old might be back.
He'll be out for at least a few months. It's obviously very disappointing news, says Postecoglou and continues:
We didn't think it would be that serious, and the medical team thought it looked okay. But then it swelled up badly a few days later, so then we realized something was wrong.
Postecoglou didn't want to set a date for when the Swede might be back, but didn't rule out that Kulusevski might be out even at the start of next season in August.
I only have basic information about the recovery, but it will definitely take some time.
Even Lucas Bergvall is injured and looks likely to miss the Europa League final against Manchester United on May 21.
In September, Sweden begins the World Championship qualifiers against Slovenia.
