Rasmus Hojlund makes his first start of the season as Erik ten Hag makes four changes to the Manchester United side beaten 3-0 by Tottenham.
Kobbie Mainoo is not involved after going off injured in that heavy home loss, while Manuel Ugarte, Alejandro Garnacho and Joshua Zirkzee all drop to the bench.
Casemiro, Christian Eriksen and Amad Diallo come into the starting XI.
Manchester United XI: Onana, Mazraoui, De Light, Martinez, Dalot, Casemiro, Eriksen, Diallo, Fernandes, Rashford, Hojlund.
Subs: Bayindir, Heaton, Evans, Lindelof, Maguire, Collyer, Gore, Ugarte, Antony, Garnacho, Zirkzee.
Porto boss Vitor Bruno makes just one change to the XI that started their 4-0 win over Arouca on Sunday.
Canadian midfielder Stephen Eustaquio replaces Nicolas Gonzalez.
Porto XI: Costa, Joao Mario, Ze Pedro, Nehuen, Moura, Varela, Eustaquio, Nico, Pepe, Galeno, Omorodion.
Subs: Ramos, Djalo, Grujic, Fabio Vieira, Vasco Sousa, Ivan Jaime, Namaso, Andre Franco, Deniz Gul, Martim Fernandes, Goncalo Borges, Rodrigo Mora
