Lavia was outstanding in midfield, while Palmer shone and scored from the spot for the 3-1 win.
Maresca said afterwards: "Probably from the outside but we saw Cole day-by-day on the training ground and he is exactly the same way, scoring goals and happy. Enjoying the session.
For sure, when he is not scoring goals he is not happy and the reason why is because he probably wants to help the team and the club to reach something important."
On Lavia, he continued: You can see that we are a better team with Romeo. Unfortunately, he has been injured for most of the season. Probably in this moment he has been the difference between us and many clubs because we had many important players for us that have been injured. Romeo is one of them. Wes Fofana is another one.
"We had Nico (Jackson) for two months (out). Romeo showed again today how important he is for the team and how good he is."
Liverpool deserve to be champions
Asked about the difference a fully fit Lavia could have made, Maresca continued: "I really think that Liverpool deserve to win the Premier (League). First of all because they have been consistent. Second of all because they had consistently the (whole) squad available, something that unfortunately the rest (of the teams) have not.
"Today again they show the reason why the have won the Premier League. We did not plan, I promise you, the game to defend deep. We plan the game to high press in the way we always (do) but sometimes the opposition is so good that you have to defend deep and you have to adapt and the players dealt with that very good."
Maresca also offered more on Palmer and his form.
"He is happy for sure because he scored and because we won but I did not see Cole (being) different to two months ago, three months ago. I said many times he has scored 14 goals for us in 20 Premier League games but unfortunately he did not score many goals in the last part of the season.
"Now we have three more games and also on Thursday the second leg. Hopefully he can help us until the end."