The diminutive forward, who has played mainly in wide positions, may have the appearance of someone of even more tender years, but Lucas knows there is more to the player than meets the eye.
"His reputation is very high back in Brazil but he left the country very early so we couldn't really see him play in the first team," said the midfielder.
"At Inter he didn't have as many chances as he thought he would have so here is a new challenge for him and he is really looking forward to it.
"He is still adapting and we were talking about the pace of the Premier League and even in the training sessions he can feel it is much quicker than Italy.
"He is trying to play quick because he knows he will need that tempo to be successful.
"It will take him time to settle but a goal will give him confidence and we could see there were positive things from him.
"Hopefully he will be a great player for now and for the future as well as he is only 20."
Lucas, as a fellow Brazilian, naturally feels a certain responsibility towards Coutinho but believes the club's other South American players - Uruguayans Luis Suarez and Sebastian Coates - will also help.
And while he can pass on a huge amount of experience after more than five years at Anfield 26-year-old will skip over his first two seasons when he was the target of fans' disapproval and focus on more upbeat messages.
"Every single young player who comes to the Premier League finds it difficult and it is going to be the same for him but we have a few South American players who can help him," Lucas added.
"He has the skills and the ability to do well. We just need to keep positive with him and hopefully he will be okay.
"I really don't tell him what I went through in my early stages, I just told him how he will be successful here."
Defender Jose Enrique, who scored his second goal of the season in the win over Swansea, believes the club have the firepower to be competitive with most teams - providing they can cut out mistakes.
Statistics back up his assertion as only three other 91 league clubs have scored more than the Reds this season.
However, errors against West Brom and Zenit St Petersburg cost the Reds defeats last week but the Spaniard is hoping they can iron things out at the back in the remainder of the campaign.
"I think we are playing well. Against West Brom it was the same as Zenit, we had chances to score, made two mistakes and they scored," he said.
"We were not lucky in scoring goals and I don't know what happened, maybe we lacked concentration, but we conceded two goals.
"This can happen but we have to try to make these errors not happen again and if we can keep a clean sheet we will score in a lot of games.
"We have Luis, (Daniel) Sturridge and now Coutinho as well so I think we can score a lot of goals."