The 37-year-old midfielder made his first start for Les Parisiens in a 2-0 victory over Olympique de Marseille at Parc des Princes on Wednesday.
PSG sits atop of Ligue 1 - four points ahead of Olympique Lyonnais and eight ahead of Marseille - but, with Champions League aspirations to consider, Ancelotti wants to shuffle his squad.
"Beckham will not start," the Ancelotti told reporters in the pre-match press conference. "The players who didn't play on Wednesday will play. Thiago Motta won't play on Saturday, Maxwell will rest, Jallet suffers from an injury and will not play.
"I’ll decide after training. We have lots of players fit, I do not have many problems. I will make changes again but I wont take risks."
Reims is 17th in Ligue 1, but Ancelotti has warned against complacency, especially with Lyon lurking so close in the French top tier.
"The objective will not be easy," Ancelotti said. "Reims are good right now. I don’t think Paris has an advantage by playing before Lyon, as they are pushing us from below.
"We will have to do our best and be ready for all upcoming games."
PSG faces Valencia in the second leg of their last 16 Champions League bout with Valencia, and though it holds a 2-1 advantage (and two away goals) heading into the home clash, the club will be without suspended star striker Zlatan Ibrahimovic, who was sent off in the first leg.