The midfielder is entering his second full season at Anfield.
"Coutinho is on the list of players we want to reward and hopefully over the course of the summer that is something we can do," said the Liverpool manager.
"He's certainly a great player, and a fine asset to the club. He's come in here and shown us quality. He's really developed as a player and a person and is now moving into the best years of his life as a footballer."
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