Unlike his predecessor Harry Redknapp, Tottenham manager Andre Villas-Boas has placed winning the Europa League high on his list of priorities.
Villas-Boas won the competition two years ago with FC Porto and is expected to include Dembele in a strong team for the Group J game against Lazio, who have won all three matches in Serie A so far this term.
Spurs will then travel to Panathinaikos before hosting Slovenian side Maribor in the competition.
Dembele, who was in the Fulham side that were knocked out of the group stages last term, hopes he can progress to the knockout stages with Spurs, but knows the team's chances of progressing will improve greatly if they beat Lazio at White Hart Lane on Thursday night. "Lazio is a big team and I think Panathinaikos will be difficult too so that's why we have to win this game tomorrow so we can go (to Greece) with more confidence," Dembele told a press conference. "This is a very important competition for us. There are some good teams in this competition but I think we can do something in it." Dembele has been an instant hit with Villas-Boas and Tottenham fans since he joined for £15million on deadline day.
The Belgian came off the bench to score against Norwich on his debut and then excelled in Sunday's 3-1 win over Reading. That victory at the Madejski Stadium, Villas-Boas' first in charge, has given the squad a huge lift and Dembele expects the team to go from strength to strength. "That win was very important for us because it took the pressure off us," the 25-year-old said. "It wasn't an easy game. Reading are a good team. "We have a better spirit in the team now, there is a lot of positive energy in the squad now." Dembele, who was also thought to be on Manchester United's radar, said Spurs initially declared their interest in him "a long time ago".
The former AZ Alkmaar player is happy he moved to White Hart Lane and thinks the club could be set to achieve something special under their new manager. "I am very happy to play for Spurs now. It's a very big club," Dembele said. "I have just been here a few weeks but I have already seen that there is a lot of quality in the side we are a very good team. "I was surprised about how good they were in training and that gives me confidence that we can achieve something."