Leverkusen won their first group stage game 4-1 over BATE Borisov with two goals coming from the Turkish international.
Manchester United are preparing a €40 million bid for Çalhanoğlu according to the Dutch football outlet Soccer News.
Çalhanoğlu joined Bayer from HSV on a €15 million transfer last season and was selected as the sixth most valuable U-21 players in the world list by Soccerex.
The 21-year-old has provided one assists and scored five goals in 11 appearances for Leverkusen this season.
Kick-Off: 19:45 GMT
Stadium: Camp Nou, Barcelona, Spain
Barcelona probable starting line-up: Stegen, Jordi Alba, Javier Mascherano, Pique, Dani Alves, Andres Iniesta, Sergio Busquets, Ivan Rakitic, Neymar, Luis Suarez, Haddadi
Bayer Leverkusen probable starting line-up: Leno, Donati, Tah, Papadopoulos, Wendel, Kramer, Bender, Bellarabi, Hakan Calhanoglu, Kampl, Kiessling