Coutinho, who joined Liverpool from Inter Milan last month, marked his full debut with a goal in Sunday's 5-0 demolition of Swansea and received a thunderous ovation from Liverpool's supporters, who were impressed by what they saw from the Brazilian international.
"Every single young player that comes to the Premier League finds it difficult and it is going to be the same for him," said Lucas. "But we have already seen a lot of positive things from him. He has got the ability to do well. We just need to keep positive on him and tell him he will (eventually) be okay.
"He is still adapting. I have been talking to him about the pace here and even in training, he can feel it is much quicker than Italy.
"He will need time to settle but the goal will give him. I'm sure he will be a great player for now and for the future of Liverpool."