Firmino has become Liverpool's top scorer in all competitions this season.
Firmino is currently enjoying some rich form of late having become the Reds top scorer for the season with nine goals in all competitions - scoring eight of them since the turn of the year.
Coutinho is quoted by the official Liverpool website, saying: “He is a great player, as I always said before he arrived. The other players and I are very happy to have him with us. He is a key component in our current team.
“As Lucas has said, he is a guy that seems like he is going to score in every game, he assists, so he has been very important and I am happy to see him doing well and helping the team.
“We can see Firmino has adapted very quickly. He is an amazing guy on the field and off the field as well. We are very happy.”
Firmino's latest strike for the Reds came in the 2-0 win over Manchester United last week at Anfield - a lead which Liverpool will take into the second leg at Old Trafford tomorrow night as they bid to finish the job and reach the quarter-finals of the Europa League.
Firmino has certainly been one of the players that has had the trust of Jurgen Klopp since the German was appointed manager back in October. Whenever Firmino has been available Klopp has called upon him. There have been times when he's been asked to play wide, frequently to lead the line and other times to play a little deeper, off the front man.
Coutinho and Firmino have shown they are comfortable playing in the same side as one another when they have both been fit. Last week's first leg win over United is one example, the 4-1 win over Manchester City in November is the probably the stand-out.
Though some will see Firmino as an odd player that can often disappear in games, then reappear with devastating effect, his importance in the second half of the season can't be understated. It should also be noted that this is still his first season in English football, and the first half of it didn't exactly go smoothly. There is probably a lot more to come.