Brighton have been struggling, losing 4-0 in their Europa League round of 16 first leg tie against Roma in midweek.
But in the 1-0 win over Nottingham Forest on Sunday, De Zerbi saw great signs.
He told club media: I'm very happy for the reaction to Thursday but I had no any doubts about the human quality of my players.
We were suffering after Thursday evening and we showed fantastic pride and character, but that is not a surprise from this group of players. The three points are important and so is the reaction after three defeats, the last two very tough. It is important to keep our position in the table and the level of these players is incredibly high.
The challenge is to do our best in every game. We can play better and have played better in the past. At the moment we are not perfect in terms of physical condition and number of players, so I am pleased with what we are showing.
I think we played a good game, especially in the first 35 minutes. After our goal we suffered sometimes more but we only conceded two shots and (they were) not clear chances for them to score. Now we have to prepare for Roma and play a serious game."