Bergvall was absent from the matchday squad for the 3-1 win against Bodo/Glimt after sustaining the issue ahead of the first leg of their UEFA Europa League semi-final.

The 19-year-old put pen to paper on a new deal with Spurs earlier this week, extending his stay in north London until 2031 after a breakthrough year.

Bergvall has made 45 appearances for Postecoglou's team across all competitions, scoring one goal and registering four assists.

"Lucas, it looks like the injury is significant to keep him out for the rest of the season. He tweaked the ligaments in his ankle," Postecoglou said. 

When asked about how the injury occurred during training, Postecoglou added: "It wasn't a tackle, he went to turn and his ankle gave way. They are things that happen.

"He is hugely disappointed and there isn't much you can say. Every experience in life and football makes you stronger. He has an unbelievable career ahead of him.

"It has denied him the opportunity to play in a big game last night. He will come back stronger. Every player has to go through setbacks."

The Spurs boss also offered updates on Dominic Solanke and James Maddison, who were forced off with knocks during the win at Tottenham Hotspur Stadium in midweek.

"Dom [Solanke], we don't think it is anything too serious. He is a doubt for the weekend," Postecoglou continued.

"[James] Madders is a bit more of a concern as it is the knee. We have sent him for a scan and are waiting for the outcome.

"Son is out on the grass and feels better every day. We will see about Thursday."

Spurs travel to London Stadium to face West Ham United before making the trip to Norway to take on Bodo/Glimt in the second leg of the European tie.