Adebayor is the only forward in Tottenham's squad with the natural attributes to play as a lone frontman in Andre Villas-Boas's preferred 4-2-3-1 system.
"It's a big loss for us because he has a lot of quality," said Gallas. "He can keep the ball, he can score, and having him means we can play the long ball or the short ball.
"Against Arsenal it was really difficult to stay in the game because Adebayor was sent off but in other recent matches, like against Manchester City and Chelsea, I think we've missed something. We have to work hard again and try to come back."