Forest are 16th with 33 points, three points above the relegation zone. Steve Cooper's side have been in and out of the drop zone in recent weeks but two wins in their last three games have given them a boost in the home stretch.
Chelsea ended a nine-match winless run in all competitions when they beat Bournemouth last weekend -- Lampard's first win as interim boss -- but the former midfielder said that was just a "small step forward" for the London club.
"I think in football it can (change the mood) but we cannot get carried away with a win," Lampard told reporters ahead of Saturday's home game.
"Another game comes in the Premier League against a team fighting for their lives.
"It's a big test, we have to give them (Forest) complete respect. They have an effective way of playing. They are very threatening in terms of set pieces and fighting for everything."
However, Ben Chilwell will not be involved after he injured his hamstring, joining Reece James and Mason Mount in potentially sitting out the rest of the season.
"I feel for him. We miss big players. Reece, Mason and Ben are big internationals," Lampard added.
Victory for Chelsea would help Everton in the relegation battle with Lampard's former side one point behind Forest while his team could also have a say in the title race when they face league leaders Manchester City later this month.
"Maybe, but Everton's fate is in their own hands at this point," Lampard said.
"It's not in my concerns. I lived that life last year. I have a lot of connection to the club and the year that I had there was a really enjoyable time for me.
"We play for pride in every game no matter what the consequences for anybody else. It's our consequences that we are concerned about."
