Chelsea picked up a second straight win for the first since December thanks to second-half goals from Reece James and Enzo Fernandez, before Gabriel Pereira got one back for the hosts.
"It was a little bit of a sloppy goal (we conceded), we could’ve avoided that. But it’s football, it can happen ... we're happy we won," Maresca told reporters.
"But the most important thing is Sunday’s game."
Fifth-placed Chelsea, who host Leicester City on Sunday, sit a point behind Manchester City in a race to secure the Premier League's fourth automatic Champions League slot for next season.
"From now on every game is important and if we can win against Leicester on Sunday we can take one more step towards our target, which is finishing in the Champions League positions," Maresca said.
The manager said defender Malo Gusto might still be available for Sunday despite being forced off with an injury in the first half.
"He’s okay, he’s better. They just said to me he could possibly be available for Sunday’s game, so hopefully we will have him for Sunday," Maresca added.
