Saints visit Stamford Bridge on Tuesday night with Chelsea licking their wounds after defeat at Aston Villa on Saturday.
The match was marked by a poor error from Jorgensen, who had been declared Chelsea's first-choice keeper ahead of Robert Sanchez by Maresca going into the game.
This morning, the Italian stated: "He is okay. He feels a little bit sad and upset because he recognises it was a mistake but overall he is okay.
"If we need to change players every time there is a mistake, we will change many players but no, nothing has changed."
On his team's current form slump, Maresca insists the Villa defeat was an improvement on the previous week. The Blues now sit in seventh place, though only a point behind fourth place Manchester City.
And the Blues manager insists it's important to stay positive.
"It's like this. We ask for a better performance compared to Brighton and I think that was there. We didn't deserve the final result but we need to accept that. It's not enough - we need to find something extra to get results, but we will be there.
"There have been bad ones, good ones, but it was just after the game and now it's gone. We will think about the next one."
Maresca was asked what would happen if they were beaten by bottom-of-the-table Southampton and he insisted no-one at Chelsea are underestimating the visitors.
"When you are at Chelsea, you don't have games you don't prepare to win. Our duty is to prepare every game to win. We have 12 games to go and all of them are must-win for us.
"It is football. You are older than me, I guess, and you know better than me that football is full of these kind of things. If you see a few games ago, the Man United one, they were winning until the end but Man United won the game."
Chelsea had the lead at Villa Park before the hosts overran them after halftime. Maresca concedes defending a lead is an issue for his young team.
He continued: "I don't have an answer for that. I knew this that we dropped 13 points from winning positions. Sometimes it's football. We are trying to understand a little bit. The good thing is at least you were in front but now it is the other part, being in front and trying to protect that. We analyse we have chances to go from 1-0 to 2-0 and we miss more than once. If you miss, the game is always open and anything can happen."
However, Maresca was again keen to stress the improvement he was seeing from the players, insisting the team is now showing the "identity" in their play he is eager to bring through.
"Even against Villa, the identity was there; the way we played on and off the ball was there. The identity is there, but in this moment it is a matter of results. I have the feeling that winning one, we can have a good run again, good momentum again. This is what I feel like the players need in this moment."
On what he wants to see improved against Saints, Maresca admits they need to be better in both boxes. The manager says their defending must be better - as should be their finishing.
After admitting Pedro Neto could feature as a No9 given their injury issues in attack, Maresca added: "Probably there are always more than one reason (for the form slump).
"In the last seven, eight, 10 games, the huge difference for me has been especially inside the box - both boxes. We always create chances so the difference has been inside the box. We need to be defensively more strong and more clinical when we get the chance."