Benitez’s spirited side came from two goals down to draw 2-2 with West Bromwich Albion last night.
Benitez, looking to end a four-game losing run, changed almost half his team.
Mikel Merino, Ayoze Perez, Karl Darlow, Isaac Hayden and Chancel Mbemba were all recalled to his starting XI.
“It’s just that when you play two games in a few days, you need fresh legs,” said United manager Benitez.
“For everyone, they need to be sure that they will be part of the team, part of the season, and they need to know they can help the team. Now everybody knows that they can play.”
Benitez handed Darlow his first league start of the season at the expense of Rob Elliot, who had been an ever-present in goal.
Asked about the decision, Benitez said: “It was just to change things and make sure that everybody could be part of the team.
“Everybody knows that they must continue working hard in the training sessions and perform in the games to make sure they can carry on playing.”
Newcastle take on Premier League champions Chelsea at Stamford Bridge on Saturday.
“Obviously, we know that it will be very difficult, but the reaction of the team means we can be positive in terms of how we approach the game,” said Benitez.
“We know that we can do well and it’s just a question of being focused, stay concentrated and don’t make the mistakes that we did against Manchester United, who is a top side.”