Amid a defensive injury crisis, Sarri has every confidence in Denmark defender Christensen stepping up.
"Christensen during the season has played about 25 matches, so he is ready," said Sarri.
"I hope he will be very fresh, mentally and physically. But I am sure he is ready to play in every match. It's not a problem. The problem is only the number, because we have only two fit centre-backs.
"But I'm really very confident with Andreas because he's ready. He's played very important matches very well, so Christensen is not a problem for us, the problem is the number at the moment."