Morris, who was Lampard's right-hand man during his time in charge at Stamford Bridge between 2019 and 2021, has confirmed Christensen did the same while they were there.
Speaking to Stadium Astro, he said: "To be fair we experienced that [pulling out of matches] ourselves when we were here working with Andreas.
"You never know what some players are going through. Whether it be nerves, whether it be something off the pitch.
"We experienced it a few times with Andreas but I don't think he's the only player who experienced it.
"He's probably more honest about that sort of side of it."
Christensen will leave Chelsea at the end of the season when his contract expires.
He is expected to join Barcelona on a free transfer.
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