The Brazil international linked up with the Reds from Bundesliga outfit Schalke in a deal worth £29m two years ago.
And, under Jurgen Klopp, he’s established himself as a firm fans’ favourite due to the threat he offers and his work-rate.
Firmino has spearheaded Liverpool’s attack for much of the past year, flanked by the likes of Sadio Mane, Philippe Coutinho and Mohamed Salah.
In that time he’s scored 16 goals, two of which have come in four Premier League appearances this term.
Comparing Firmino to the likes of Sergio Aguero, Harry Kane, Romelu Lukaku and Alvaro Morata though, Nicholas has suggested the 25-year-old lacks the killer instinct that quartet possess.
Nicholas told Sky Sports: "My personal favourite [striker] is still Aguero.
"Kane probably has more about him in terms of being strong, good in the air, but when Aguero runs at people, which he's not been doing for a couple of years, he has the balance, technique and confidence which elevates him into that world class bracket.
"Those are the occasions where Kane would just take on the shot but Aguero can pierce you with his movement and skill. When he's on his day, he's up there with Luis Suarez, Cristiano Ronaldo and Lionel Messi, whereas as Kane doesn't quite have that magic.
"I'm a big fan of Roberto Firmino as well but he's not a natural goalscorer like the others."
Firmino started in attack for Liverpool in last night’s Champions League showdown with Spartak Moscow.
The former Figueirense man missed a great chance in the first half when he failed to connect properly with a whipped Jordan Henderson cross.
