With Felix now on-loan AC Milan, Chelsea have been hit by injuries to attacking pair Nicolas Jackson and Marc Guiu.
But Maresca said after their 2-1 loss: "I don't think we miss Joao. Joao is happy there and we are happy Joao is happy there. The only thing I can say is no-one would predict on deadline day we had two strikers injured. This is something that is difficult to think. It unfortunately happened but we have Nico to be back very soon.
"Yeah, for sure, it is a shame, no doubt. We see how complicated this competition is. We see big clubs against Championship, League One, how difficult this competition is. It is a big shame for us but probably, as I said, if there is something positive it is that we can be focused on the Premier League and Conference, especially in the Premier League. Hopefully we can continue our journey there that for me, has been very, very good until now and hopefully we can finish well.
"For me, a good season is seeing the team improving game after game; go through bad moments through difficulty - it is the only thing I think that can bring this club to compete for something important. This is exactly what I think.
"As I said, we can now be focused on the Premier League and Conference. Hopefully we can finish in the right way."