O'Nien is still yet to play a minute in the Premier League after missing the early weeks of the season through injury and having had to settle for a place on the bench since his return.
And Le Bris admits he "doesn't know" what sort of role the experienced defender - who has played more than 300 games for the [Black Cats](http://www.thenorthernecho.co.uk/sport/football/sunderland?ref=au) - will have on the pitch this season.
[Sunderland](https://www.thenorthernecho.co.uk/sport/football/sunderland/?ref=ed_direct) strengthened their backline in the summer with the arrivals of Nordi Mukiele and Omar Alderete, who have both quickly established themselves as major forces in Le Bris' side, while Lutsharel Geertruida, who made his first start of the season at Stamford Bridge in last Saturday's win over Chelsea, is also above O'Nien in the pecking order.
But that doesn't mean O'Nien's presence isn't still valued by Le Bris, who says the defender has a crucial role even when he's not playing.
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After four games as an unused substitute in the Premier League, O'Nien got some crucial match minutes under his belt with 90 minutes for Sunderland's Under-21s in the Premier League International Cup draw with RSCA Futures at the Stadium of Light on Wednesday night.
He'll be in the first team squad for Monday's Premier League game against Everton but is again likely to have to settle for a spot among the substitutes.
Asked what sort of role O'Nien will play on the pitch this season, Le Bris said: “At the minute, we don't know. But what we know is that we need a full group with a positive energy and everyone knowing his own role.
“Even if you don't play, you are important for the squad with positive vibes, the way you train every day, the standards you are setting with this idea to get better every day.
“Luke is like that, he's really positive. After that, he's versatile. He can play as a centre-back, he can play as a full-back, right, left, so he has the potential to help the squad."