Coutinho has been linked with a move to the Catalan giants all summer but the Premier League club has refused to sell.
That has led to a protracted war of words between the clubs and some off-field sulking from the player.
The 25-year-old has missed Liverpool's opening Premier League fixtures with a back injury but miraculously recovered in time for him to star in Brazil's 2-0 win over Ecuador on Thursday night.
Coutinho came on as a 59th minute substitute with the scores level before watching Barcelona's new midfielder Paulinho score and then bagging one of his own seven minutes later.
"I'm very happy because he has scored a goal," Neymar, who left Barcelona to join PSG in a world record transfer this summer, said after the game.
"At this moment he lives a very great sadness, but he helped us in the victory.
"He’s a great player, a superstar, and he entered the match very well [from the bench]."
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies