Spurs currently sit in third place in Group J after draws in all three of their opening games.
However, a win against NK Maribor at White Hart Lane on Thursday would give the team a good chance of making it through to the next round of the competition.
"It's in our hands and that's all you can ask for," said Dempsey.
"Everything is still to play for and it's about taking care of business in the next three games."
Tottenham drew their previous meeting with Maribor 1-1 in Slovenia last month.