The outgoing winner, Slovenian Tadej Pogacar, withdrew from Liège-Bastogne-Liège on Sunday, his UAE squad announced on the eve of the race.
Pogacar, double winner of the Tour de France, returned to Slovenia on Thursday to support his partner who has suffered from family bereavement.
The Slovenian will be replaced in the Dean of the Classics by the American Brandon McNulty, said the Emirati team.