Maddison missed the end of Spurs' injury-ravaged 2024-25 campaign under manager Ange Postecoglou with a knee injury, but returned last month to feature in pre-season under new boss Thomas Frank.
Maddison continued his comeback with a substitute appearance in a 1-1 draw with Newcastle in South Korea on Sunday, but collapsed in pain with no one around him and subsequently left the pitch on a stretcher in the 86th minute.
Spurs' worst fears have now been confirmed with Maddison set to undergo surgery in the coming days on his ACL injury.
"We can confirm that James Maddison will undergo surgery for a ruptured anterior cruciate ligament (ACL) in his right knee," a club statement read.
"The 28-year-old midfielder suffered the injury during our pre-season friendly against Newcastle United on Sunday in Seoul.
"His surgery will take place in the coming days and, following that, James will then begin his rehabilitation with our medical team.
"Everyone at Tottenham Hotspur wishes James a full and speedy recovery. We will be supporting him every step of the way."
This news will be a major blow to Frank, who was already light on attacking midfielder options with Dejan Kulusevski set to miss the start of the season after he had surgery on his right patella in May.
Spurs failed in their efforts to tempt Morgan Gibbs-White away from Nottingham Forest in July and now face greater urgency to sign an attacking midfielder.
No timeline has been provided for Maddison's recovery, but an ACL injury tends to sideline a player for between six to 12 months and could rule the England international out of next summer's World Cup.
Maddison ruptured his ACL in Son Heung-min's final match for Tottenham before his move to Los Angeles FC.
The departure of Son, Spurs' captain last season, and the prolonged absence of vice-captain Maddison will also take away a wealth of experience from Frank's squad ahead of a campaign where they will be expected to juggle Premier League and European commitments better than they managed in the injury-hit 2024-25 term.
