The Colombian, who came off the bench to score in the 4-0 Scottish Premiership win over Hearts last weekend, replaces Antonio Colak, who started and scored a brace in the same game.
Giovanni van Bronckhorst has made a total of four changes to his starting lineup, with Leon King, Steven Davis and Malik Tillman all coming in at the expense of Ryan Jack, Rabbi Matondo and Scott Arfield.
There could also be a change of formation for the Gers, with King potentially slotting into the back three alongside Connor Goldson and former Liverpool man Ben Davies, with captain James Tavernier and Borna Barisic operating as full-backs.
Former Everton youngster John Lundstram is joined in the middle of the pitch by 37-year-old Davis, while Kent and Tillman will provide support in attack for Morelos.
Van Bronckhorst has also decided to stick with 40-year-old goalkeeper Allan McGregor ahead of Jon McLaughlin.
As for Liverpool, Jurgen Klopp has made three changes to his first XI, with Darwin Nunez, Diogo Jota and Luis Diaz all returning, while Fabinho, Fabio Carvalho and Roberto Firmino have dropped to the substitutes' bench.
Liverpool starting lineup: Alisson; Alexander-Arnold, Matip, Van Dijk, Tsimikas; Thiago, Henderson; Salah, Jota, Diaz; Nunez
Subs: Adrian, Kelleher, Gomez, Fabinho, Konate, Milner, Firmino, Elliott, Ramsay, Carvalho, Bajcetic, Phillips
Rangers starting lineup: McGregor; Tavernier, King, Goldson, Davies, Barisic; Lundstram, Davis; Tillman, Morelos, Kent
Subs: McLaughlin, McCrorie, Ridvan, Devine, Jack, Kamara, Arfield, Colak, Matondo, Wright, Fashion