Mundle made his long-awaited return from injury at the weekend when he came off the bench for the final half an hour of the comeback victory over Bournemouth.
It was a first appearance of the season for Mundle after summer hamstring surgery, which followed an injury-disrupted campaign in which the winger was limited to just 17 Championship starts.
Mundle will almost certainly have to settle for a place on the bench again at Anfield on Wednesday night, but the winger's return to action is timely considering Sunderland will lose three wingers later this month when Chemsdine Talbi, Bertrand Traore and Simon Adingra all head off for the African Cup of Nations.
"It's important because we know the wingers are important in our system, I think in every system, because you need creative, impactful, strong 1v1 players," said Le Bris of Mundle's return.
"And I think he's one of these players. He struggled for a long period last season because of his injury. Get back after this surgery. And his mindset is perfect because he's a big challenger at the minute.
"It's really important for us. Good for the competition as well, because we need definitely these two or three players able to be competitive. It shows that if you are not at your best, the other can be on the pitch and pushes you all the time."
Dennis Cirkin and Leo Hjelde continued their comebacks from injury with another outing for the Under-21s in the Premier League Cup victory over Bromley on Monday night. The pair are "really close" to being back in first team contention, said Le Bris.
"It's really important to have everyone connected and in the best shape so they are ready," said the head coach.
Noah Sadiki suffered a badly swollen lip after being on the receiving end of an elbow from Bournemouth's Lewis Cook at the weekend, but the midfielder will be fit to feature at Anfield. Le Bris has no fresh injury concerns.
"Noah suffered and it's still the case now," Le Bris said.
"He will be OK for Wednesday, but yeah, he suffered."
Meanwhile, Arne Slot must decide whether to recall Mo Salah after the Liverpool forward was left out at West Ham on Sunday.
Asked whether Salah had been unhappy with the decision, the Reds boss said: “That is a fair assumption and a normal reaction from a player that is good enough to play for us.
“Of course a player is not happy he isn’t playing. He was not the only one who wasn’t happy he wasn’t starting, I can tell you – and that’s normal.
“But the way he behaved is what you would expect from the professional he is. He was very supportive for his team-mates, handled himself really well during the day and yesterday in the session as well.
“You cannot be a player that’s available every three days and play at those high standards if you go with your emotions but Mo is so disciplined.
“No matter if he plays well or if he doesn’t play he will always be that top professional and that is what he’s been in the last few days.”
With Salah having only four more games before he heads to the Africa Cup of Nations on December 15, with the potential for him to miss at least seven matches should Egypt reach the final, Slot has to get the most out of the player.
He will likely return to the starting line-up for the visit of Sunderland on Wednesday but such was the success of the remodelled formation, with Florian Wirtz impressing as the number 10 and Dominik Szoboszlai on the right with Alexander Isak up front, Slot may be tempted to go with it again at Leeds on Saturday.