Welsh wizard Bale will miss at least two weeks after being carried off with an ankle injury in Spurs’ 2-2 Europa League draw with Basel on Thursday.
It is feared their bid to qualify for next season’s Champions League will be doomed without him.
But midfielder Dembele believes that is not the case.
The Belgian said: “Can we make the top four without Gaz? Yes, of course we can.
“There are other good players who play well. He has been very important for us but other players have to step up now.”
Dembele, 25, is backing his former Fulham pal Clint Dempsey to fill the void left by Bale, Lennon and striker Jermain Defoe — who will be out for another two weeks with a groin problem.
Dembele and Dempsey cost Spurs a combined £21million when they moved across London last summer.