First-half goals from Luka Stojkovic and Dion Beljo inflicted another setback on the Black Cats, further intensifying scrutiny of the French tactician.
Despite an improved second-half performance that saw the hosts strike the woodwork three times and have a Wilson Isidor effort ruled out for offside following a VAR review, they failed to overturn the deficit at the Stadium of Light.
The DR Congo international admitted that the team’s recent performances have fallen well below expectations but was adamant that Le Bris should not be made the scapegoat for their struggles.
"I don't think the gaffer is the problem," Sadiki told the media in the mixed zone.
"We are on the pitch, we are making mistakes, he's not making mistakes. He's putting the players (on the pitch) and the players have enough quality. That's why they're all here. I don't think the gaffer is a problem.
"We owe it to him, and we owe it to ourselves as well. We owe it to the fans. We owe it to everybody who comes to support us every weekend and every European game.
"We're letting a lot of people down. We're letting ourselves down as well sometimes. We need to step up in the next game."
Sunderland's latest setback comes after their 3-1 Premier League defeat to Coventry City.
Captain Granit Xhaka had previously questioned the side's repeated mistakes, suggesting that discussions would count for little unless accompanied by improvements on the pitch.
Echoing those sentiments, the Congolese star admitted that words alone would not reverse the club’s fortunes.
"I don't think talking solves anything if you don't put the actions on the pitch," Sadiki explained.
"Talking is good because you make people think of their actions. But if it doesn't follow on the pitch, it's a little bit useless."
Despite the growing frustration among supporters, Sadiki rejected suggestions that anxiety had taken hold of the dressing room, stating that the players still possess the quality and character that underpinned their previous successes.
"Things are not going our way. We are not putting the effort that we need to put. We need to get back on the same page, pushing in the same direction, even though it's difficult," the midfielder continued.
"I don't think the quality is gone. I don't think the morale is gone. It's a difficult moment.
"That's now when you need to have your leaders, have the guys with character to step up."
He was equally understanding of the disappointment expressed by Sunderland supporters following another frustrating evening on Wearside while looking forward to the Chelsea fixture.
"It's understandable. It's really understandable that they are not happy at the moment," he added.
"You see that we are not at 100% of our qualities right now. Everyone on the team is on another level right now. We need to step up.
"Every time we lose, every game becomes bigger and bigger.
"Chelsea is a big game. We have two or three days to reflect on what we did today. We need to give our best to the game.
"You can't stop fighting. Because if you stop fighting, you can just tell the Premier League that we don't want to play anymore and we give it up.
"We need to stick together as a team. It's the only thing we can do. Go back to the basics. Do our basics right."
