The big spenders suffered a huge shock in midweek when dumped out by Evian but can consolidate their place at the top in France with victory on Sunday against Claude Puel's Champions League chasers.
Ancelotti pulled no punches with a damning assessment of the cup defeat, describing it as a "disaster", and urged his big-money signings to get back on track.
"I hope they will learn their lessons from the game against Evian TG," he said. "This year, we didn't have any problem beating the biggest clubs.
"We've had fantastic games against them."
The former Chelsea manager added: "We've won against the best clubs in the league; we were excellent in Champions League, yet we've had issues against supposedly weak clubs.
"On paper, these games were supposed to be easy. In reality, those games happened to be very hard."