But Lampard was hopeful the American's injury wasn't serious.
He said: "Christian felt some tightness in his calf during the second drinks break so we took him off straightaway.
'We will see the extent of that over the next couple of days but hopefully that won't be anything serious."
Andreas Christensen was also omitted from the match-squad due to a hip injury.
"With Andreas, he had a small problem near his hip," Lampard added.
"He tried to train yesterday but didn't feel comfortable, so we pulled him out of the squad."