The Scottish champions moved above their Dutch opponents into third place with the 2-0 win last time out and Lennon believes his side's promising performance at AC Milan earlier in the competition shows they can prosper at the Amsterdam Arena.
"The game in Amsterdam is pivotal," he told Celtic's official website.
"It's a huge game and we started working on it - the team selection and the way we'll play - as soon as Saturday's game finished.
"If we can play like we did in Milan, then we've got a good chance.
"But you can never predict these games. Ajax are a class side, very fluid with the ball and they will create chances, but I think we can create chances too.
"We'll have to be positive, and to get something out of the game would give us a great chance in the last two games.
"I think the atmosphere will be fantastic, but it's the Champions League and I don't think the players need any extra incentive to play there."