Spurs lead the French side 2-1 following last week's game at White Hart Lane, and the veteran stopper reckons that the balance in favour of Andre Villas-Boas's side.
"The second goal was very important because 1-1 going to Lyon might tip the balance to them, but at 2-1 it gives the balance to us," Friedel told the club's official website.
"It's two good teams both trying to progress and it's by no means a massive advantage, just a small advantage. They are going to have come out and try to score and hopefully that will leave it a bit open at the back and could leave chances for us.
"I'm sure it's going to be a great second leg. The knockout stage of the competition is when these games really come alive and we're looking forward to it."
Two Gareth Bale free kicks were enough to give Spurs the lead heading into the second leg.