The Uruguay striker Cavani picked up the knock in training in the build-up to Saturday’s 4-1 win over Newcastle.
Ole Gunnar Solskjaer says Cavani will be sidelined for a “week or so”.
Nineteen-year-old Anthony Elanga is included in the 22-man squad,
alongside 21-year-old goalkeeper Matej Kovar.
Portugal forward Ronaldo, has been named in the squad for his first Champions League trip with the Reds since featuring in the 2009 final.
Manchester United travelling squad
De Gea, Heaton, Kovar, Bailly, Dalot, Lindelof, Maguire, Shaw, Varane, Wan-Bissaka; Fernandes, Fred, Lingard, Mata, Matic, Pogba, Sancho, Van de Beek; Elanga, Greenwood, Martial, Ronaldo.