The Blues will face United on the back of victory over Brighton.
Maatsen told the club's website: "We always used to create chances but yesterday we came in a good way up front and we did well.
"I think we just need to keep going like this. We need to have time to get to know each other and it will come. It's just about time, but yesterday we showed we can create and finish chances very well.
"Obviously today gives us a good spirit moving forward to Man United, but it's going to be a different game so we're going to prepare as we always do.
"Of course yesterday we enjoyed the win, but today we are back at Cobham to reflect quickly on this game, get the positives out of it and then bring this good spirit to Man United."