Paris Saint-Germain midfielder Blaise Matuidi led the Ligue 1 champions' complaints about the pitch at Chamois Niortais after their 2-0 win in the Coupe de France.
Javier Pastore and Edinson Cavani scored late on at Stade Rene Gaillard to beat the Ligue 2 hosts, but Matuidi felt the game should not have gone ahead.
"It was unplayable," the France international told reporters. "In this sort of situation, there had to be another solution.
"But we showed that we not only possess talent but also mental strength. To win this competition, you have to come through matches like this one.
"I think the coach also deserves a lot of credit. He knows how to handle games like this one and gave us the necessary determination."
Matuidi also praised Pastore after the Argentina international scored one goal and made the other as he continued his return from a muscle injury.
"Javier is a very important player for us," he said. "He has now returned and I hope that he will be able to find his form and keep it."
Pastore said it had been "a very difficult match -- a real cup game" and added: "We tried to play, but it was complicated.
"I feel good, that is the most important thing. I scored and was able to help the team. I played quietly, I feel very well and nothing bad happened.
"After all of the work that I have done, it was a reward to come on and score here. My season has now begun and it is at the most important moment of the campaign."
Lucas was a late substitute and saw his goalbound effort stopped by a puddle of muddy water with the goalkeeper beaten.
"It was tough," he said. "It rained all day and the pitch was difficult. But sometimes it is a good thing to experience matches like that."