Chelsea had the lead through through an own goal from Brighton goalkeeper Bart Verbruggen. However, the Seagulls fought back to win 2-1 thanks to efforts from Georginio Rutter and Kaoru Mitoma. Chelsea felt Mitoma's winner should've been disallowed for a handball incident in the lead-up.
Maresca said afterwards: "We controlled much better the first half. The second half the only shots they had we conceded a goal from.
"I think the handball is quite clear. In the last two or three days there were many different moments in different games. Without VAR it's complicated.
"We tried to come here and make our game. We had a few chances at 2-1. Now we can focus on the Premier League and Conference League.
"We always try to win the games. But in the same way you have to take the consequence of the result."