The Argentine World Player of the Year damaged a hamstring in last week's 2-2 first-leg draw in Paris and sat out Saturday's 5-0 league win against Real Mallorca.
He was given the all-clear by medical staff earlier on Wednesday but coach Tito Vilanova decided to keep him in reserve and deployed Cesc Fabregas in Messi's roving forward role with David Villa and Pedro joining him in a three-pronged attack.
PSG also left David Beckham on the bench after he started last week's first leg.
Meanwhile Bayern Munich have prolific strikers Mario Gomez and Claudio Pizarro on the bench for the trip to Juventus, with the new German champions 2-0 up from the first leg at the Allianz Arena.
Mario Mandzukic starts as a long striker, while Andrea Pirlo will attempt to pull the strings for the Italian champions from midfield with Mirko Vucinic and Fabio Quagliarella in front of him.
Barcelona: Víctor Valdés, Daniel Alves, Piqué, Jordi Alba, Adriano, Fàbregas, Xavi Hernández, Iniesta, Busquets, Villa, Pedro Rodríguez. Subs: Pinto, Bartra, Montoya, Thiago Alcántara, Song, Alexis Sánchez, Messi.
Paris Saint-Germain: Sirigu, Thiago Silva, Alex, Maxwell, Jallet, Verratti, Pastore, Thiago Motta, Lucas, Lavezzi, Ibrahimović..subs: Douchez, Sakho, Armand, Van der Wiel, Chantôme, Beckham, Gameiro.
Referee: Bjorn Kuipers (Netherlands)
Juventus: Buffon; Barzagli, Bonucci, Chiellini; Padoin, Pogba, Pirlo, Marchisio, Asamoah; Vucinic, Quagliarella. Subs: Storari, Caceres, De Ceglie, Peluso, Giaccherini, Matri, Isla.
Bayern Munich: Neuer; Lahm, Dante, Van Buyten, Alaba; Schweinsteiger, Javi Martinez; Robben, T Muller, Ribery; Mandzukic. Subs: Starke, Rafinha, Boateng, Shaqiri, Luiz Gustavo, Pizarro, Gomez.
Referee: Carlos Velasco Carballo (Spain)