Coutinho had been a doubt before the match with illness and didn't travel with the squad to Stoke yesterday.
But the Brazilian playmaker met with his team-mates this morning at the team hotel and declared himself available to play.
Liverpool fans fume at starting XI to face Stoke City
Sat, April 8, 2017
Liverpool fans react on Twitter as the Reds announce their starting XI to face Stoke City at the bet365 Stadium (3pm)
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Liverpool fans are not happy about the starting XI to face Stoke City
Firmino was also named as a substitute surprisingly, but Klopp insists both were available to come on if needed.
He told Sky Sports: "Philippe came to the hotel this morning, we left him at home because he had a bit of a temperature.
"Since this morning he's been available, he's on the bench it's good to have the option.
Liverpool duo Philippe Coutinho and Roberto Firmino
"With Roberto he has felt the intensity of the last few weeks in the last game.
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"Now is not the best moment to leave them both out but I don't make the decision, it's their bodies.
"So it's good that we have them available. It's not a major issue with [Firmino] but he's been overplayed [and is] tired."