Kuyt sustained a calf injury in Sunday's 4-0 win at Burnley while Ngog has a hamstring strain which has developed as a result of a back problem which forced him off in the first leg in Madrid last week.
It means Ryan Babel is likely to be asked to play in the lone striker role.
Midfielder Maxi Rodriguez is ineligible, having already played in Europe for Atletico, so that could mean Steven Gerrard is asked to play on the right with Alberto Aquilani given a chance in the hole behind the striker.
Kick-off at Anfield is at 8.05pm.
Reds (from): Reina, Johnson, Carragher, Kyrgiakos, Agger, Lucas, Mascherano, Gerrard, Aquilani, Babel, Benayoun, Ngog, Kuyt, Cavalieri, Degen, El Zhar, Pacheco, Ayala, Plessis.