Central midfielders Tyler Adams and Marc Roca both made strong debuts as the Whites came from behind to beat Wolverhampton Wanderers 2-1 at Elland Road.
But Klich showed his value too, coming off the bench to play in front of the pair and reasserting a control the hosts had lost after the interval. He played a part in the winning goal, which if Rayan Ait-Nouri had not put through his own net, Brenden Aaronson - the pick of the Leeds debutants - would have.
Leeds coach Marsch has been open about how Klich could move on this summer because of his desire for regular football in a World Cup season, but his performance from the bench could have made that harder.
"I was a player," said Marsch. "I know what it's like as a player to be pissed off with your coach or frustrated with a game or a team-mate so none of this is really personal.
"Klichy and I have had good discussions and sometimes disagreements on things but I like him a lot and I like guys who say what they think. Klichy says what he thinks!
"He and I have a good understanding. I like him as a player and it's just about putting together the puzzle of what we want our team to look like and how does each piece fit. I felt strongly we were going to need him today and I spoke to him before the match about what the role could look like.
"He showed his quality and played quite well and helped us in a good moment.
"One of Klichy's qualities is he can run and I knew we were struggling to cover spaces where Neves was and to pick up second balls.
"Right away he helped to settle things down a little bit and he was in some good spaces. I thought he was disciplined with his positioning and he made some good plays with the ball, including the second ball.
"I can understand some people have questioned it (Klich's future) because we haven't had him involved in certain things but let's see how things go.
"I know as long as he's here he's fully committed, that's the most important thing.
"It's clear he wants to play because making the World Cup should be a big goal of his but we also have to think about as a club what's best for us and how it all fits together."
Marsch was pleased to see his side's hard work and resilience pay off with victory. Daniel Podence gave the hosts the lead, only for Rodrigo to equalise.
"We've talked a lot about good starts and to be fair I actually thought we had a good start but we happened to just give up a little bit of a strange goal," reflected Marsch. "We said they like to play a lot of chips to the second (back) post and we don't deal well with that one (for the goal). It takes a weird bounce which doesn't allow Illan (Meslier) to have a real good read on it but even after going down we responded well, pushed the game and found the goal. In some ways we were a little bit unlucky not to find a second in the first half.
"Then to give credit to Wolves, they pushed the game really hard for the first 15 minutes and we weren't at our best, we were running too much and didn't seem to have our legs. I knew at that point making the right subs and having guys really prepared would be important.
"Klichy came in and made a big difference and Sam Greenwood as well.
"It was good to see us be resilient like we know we are and validate the good work with three points.
"Even when you watch Fulham-Liverpool you see teams aren't in top form yet so the games are going to be a little bit more in the balance so finding a way to pick up points in these early stages can help you at the end of the season when you're really fighting for positioning.
"We're more stable, we're clearer about what we want the tactics and the playing model to look like. That's going to be helpful for us."
Leeds had appeals for a first-half penalty turned down when goalkeeper Jose Sa came for a cross but clipped Rasmus Kristensen instead. The right-back was the fourth of Leeds's Premier League debutants.
"I felt live Rasmus was just taken out after the ball was gone," argued Marsch. "A lot of times they give the goalies the benefit of the doubt but if you touch the goalie as an outfield player it's always a foul.
"It looked to me like Rasmus headed it and then was taken out by the goalkeeper. If that's a defender I think it might go down as a penalty.
"I need to see it again but I'll say I think it should have been a penalty."
Opposite number Bruno Lage felt Wolves played well, and deserved better than to start their season with a defeat.
"We dominated the game and started with big confidence," said the Portuguese.
"It's a good situation we created and we scored a goal. It was disappointing the way we conceded the first goal.
"There was a good chance at the end of the first half, we refreshed our ideas and for 25 minutes in the second half we were very good but we didn't score.
"In the end I'm very proud of what my players did but it's disappointing because I think we deserved a different result."
There was touchline aggravation between the managers, something Marsch himself signposted back to the meeting between the sides at Molineux last season, but neither manager wanted to stir things up afterwards.
"Now is not the time to talk about it, I want to move on," said Lage.
"Nothing against the manager, they won and were absolutely great but there was a point in the first half I heard I didn't like and I said that to him. There are things you cannot say and I told him that.
"But Leeds won so congratulations to the manager and the fans.
"I'm very happy with my performance here, disappointed with the result."