Its hard to predict a line up, because we are strong favourites and this might be the last match in which Pep will want to divide playing time also among players who have played a bit less so far and are unlikely to start in the next stages. Next up would be probably Inter and then Chelsea/Palmeiras.
On the other hand Al Hilal are not mugs, Inzaghi gonna set them up well and in a low block. They have few players able to show magic like Cancelo.
So with that in mind I would go with:
Ortega
Khusanov Reis Gvardiol O'Reilly
Nico Gundogan Cherki
Bobb Marmoush Foden
My heart would suffer if Khusanov or Reis would not play a minute more in the whole competition. Nico and Gundogan looked good when playing, while Cherki, Bobb and Foden have all the quality needed to break low block in tight spaces.