Liverpool boss Jurgen Klopp says Alisson Becker will make his debut in Dublin.
Alisson, the most expensive goalkeeper in history, is scheduled to join up with the Liverpool squad on their training camp in France later this month, after being given extended leave.
"Obviously he is a world class goalkeeper, so we are not going to say "let's have a look". He will play, of course. When Alisson is ready, he will be in our goal. We all need to help him so he can perform as good as possible," he said.
"He is desperate to play. He could have joined us here in America but it made absolutely no sense.
"He had a long year and, as Brazil's No 1, it was quite an intense year, so I sent him on holiday again. There will still be two games to play and West Ham is only the first game of the season, not the last one.
"I would say he plays in Dublin [against Napoli]."