With La Blaugrana already 2-1 up at Camp Nou, Coutinho came off the bench to fire home his first goal of the 2021-22 season, which also marked the first time he had made the net ripple since last November.
The 29-year-old has overcome his injury woes to become a key member of Koeman's Barcelona setup, and the Dutchman has since been singing Coutinho's praises after he was linked with a move away in the summer.
Assessing Coutinho's performances in a press conference, Koeman said: "It was good. When he entered the game he was good. With his freedom we were able to control the game better. He knows how to score goals.
"He has taken an important step because I have always believed in Coutinho. Physically, he is getting better and better."
Coutinho's strike against Valencia was his 24th from 97 games in a Barcelona shirt, but the attacker has now entered the final two years of his deal in Catalonia. body check tags ::