Dembele out of north London derby
Dembele has become a key player for Spurs since his deadline day move from Fulham, but he has missed the club's last eight games with a niggling hip problem.
The Belgian had hoped to return for Saturday's crunch match at the Emirates Stadium, but manager Andre Villas-Boas has ruled the playmaker out of the game.
"Dembele does not have a chance, not for this game," Villas-Boas said.
"There is a 50% chance he will be back for the Lazio game.
"I think surgery at the moment is out of the question, hopefully."
Jermain Defoe, Aaron Lennon and Kyle Walker all suffered hamstring injuries in last weekend's 2-1 defeat to Manchester City.
Lennon appears to have been given the green light to play against the Gunners, but Villas-Boas is unsure whether Defoe and Walker will be available.
"They haven't trained with the team yet. They have had lighter sessions on their own," Villas-Boas said of the trio.
"We will have to see today how they return to see if there's any disturbance.
"Lennon had a scan yesterday, and it's fine on his hamstring."
Villas-Boas is already without long-term absentees Scott Parker, Benoit Assou-Ekotto and Younes Kaboul.