The capital-city side are neck-and-neck with Antonio Conte's men on 22 points each, and can move to the top of the league standings with three points on Saturday
The two teams are currently level on 22 points in Serie A, and the victor can go back to the top of the standings with a win.
The home side's trainer knows that it is an important game which could be decided by small margins.
"It's an important game for us and for Juve," the 66-year-old told Tuttosport.
"It is a key match. We've shown high-level performances at home and we must do it now against Juventus. It will be tough."
The race for the Scudetto is heating up with three points separating four teams at the top, but Reja feels that others are in a better position to top the pile.
"Milan have superior quality. Then there's Juve. These two teams are better candidates," the coach candidly admitted.
"We may be surprise candidates, depending on what we do in this game. A victory would give us knowledge and strength."
Miroslav Klose is once again available for Lazio after an injury lay-off, and will be partnered by either Djibril Cisse or Tommaso Rocchi in attack.
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