Former Manchester United coach Phil Neville was critical of Gary Cahill after Chelsea's 1-1 draw at Champions League opponents PSG.
Cahill provided the assist for Branislav Ivanovic's first-half opener with a neat flick inside the area.
But he appeared to be at fault for PSG's equaliser, scored by Edinson Cavani.
"Gary Cahill, as a centre back, shouldn't go outside the width of his keeper's posts," Neville said. "He got attracted towards the ball and that's why it looked like a gaping hole in which Cavani rose to score.
"From what I've seen tonight, and I'm a fan of Cahill and he's the best centre back in the England team, but he's been left out for recent high-profile games against Manchester City and Liverpool and there was hesitancy and doubt in his mind tonight.
"There were moments when a confident Cahill would have won the ball. He's feeling the pressure of Zouma, because Terry's form is not dropping.
"It's between Cahill and Zouma as to who will partner Terry."
