The on-loan Aston Villa forward came off the bench in the second-half to help the Eagles to a 1-0 win, creating Ismaila Sarr's lone goal.
Guessand told Palace's website: “When the players fight for maybe 60 minutes or even more, they are more tired, and me, on the bench, (had) more fresh legs.
“I think we saw this today because as you said, after I came onto the pitch, we scored.
“The bench sometimes is important to the team, and today we saw the result. Hopefully in the future we’re going to have more victories, because I think we deserved it.”
Guessand also reflected: “It was crazy. The game today was crazy! The two teams fought like animals.
“We saw the fans really excited for this game, because we know it’s a rivalry. In the end, Palace won, because I think we deserved this victory.
“It was a long time we haven’t won a game in the league and with the quality we have in the team, I think we deserve more. If we keep in this way, with the players we have, we can have more victories.”