Coutinho played over an hour of Wednesday night’s 1-0 third-round replay victory at Home Park, his first start since damaging ankle ligaments at the end of November.
But Coutinho could now start Liverpool’s home league game with Swansea on Saturday after setting up the Lucas Leiva header which secured the Reds safe passage to the fourth round of the FA Cup and a home tie against Wolves.
“[He] was good. I’m happy, really happy,” Liverpool manager Jurgen Klopp said of the influential Coutinho.
“It was very important for us. I thought 60-65 minutes was the perfect intensity for [Wednesday]. It was good for him and good for us.”
However, it looked a far more potent side than the one League Two Plymouth had managed to hold at Anfield 10 days earlier, with Coutinho and Origi joined in attack by Daniel Sturridge.
But Klopp bristled at the suggestion that he had named a stronger team than for the original tie, and insisted squad rotation was essential with Liverpool having seven games in 20 days.
“I named, again, the team I could name. That’s what I always do,” Klopp said.
“Only [the media] judge it as stronger or weaker, I don’t do this. It’s all about who is available.
“We play Saturday-Wednesday-Saturday-Tuesday. If I would always let the same players play, I would be a real idiot. I don’t do it.
“So, that was the team for [Wednesday]. We will see who we can line up on Saturday.”
Over 17,000 packed into a noisy Home Park, which had temporary seating installed for the occasion, and a worldwide audience also tuned in to see Plymouth prove more than a match for their distinguished visitors.
Jake Jervis almost took the tie into extra time when his volley clattered the post, but at the end there was Plymouth pride and a cup cash bonanza for the Pilgrims which is expected to be around the £1 million mark.
“Over the two games, I think the football club are proud of their players,” Plymouth manager Derek Adams said.
“The game-plan was to get them to Home Park and then see if we could win the tie.
“The players wanted to do that. They have left nothing on the pitch and made this football club very proud again.”