The Cottagers are looking to put together two consecutive wins for the first time this season following their 1-0 victory over Stoke City two weeks ago.
Meanwhile, Palace can edge closer to safety after taking just three points from their opening seven matches.
Sidwell told Fulham's official website: "It's one of those scenarios where they're always going to be the underdogs going into every game just because they've come up and the pressure is off.
"When the pressure is off you can enjoy it more and be more relaxed in your individual play.
"It's going to be a tough game, Selhurst Park is a tough place to go and hopefully we can go there and stick to a game plan that we've been working on and try to get the three points."
The last time that Fulham played Palace was back in 2005 when the Cottagers earned a 3-1 win in the Premier League.