Not a chance Weghorst doesn’t start. He has started every match since joining and works extremely hard.
I can see why some might opt for it, but can’t see Ten Hag doing so. I think he will want both Weghorst and Fred to disrupt De Jong and Busquets.
Yeah, there's no away goals, so having Sabitzer come on after an hour for a potentially 120 minute game makes sense, whereas when/if the game gets stretched, having Sabitzer or Sancho come on as a #10 could decide it (or Antony on the right and Bruno moving in to play as a #10).
I could see this from the start, though:
---Rashford---------------------------------
------------------Weghorst--------Bruno
-----------Fred--------Sabitzer----------
Shaw------------Casemiro--------------
-----------Lisandro------Varane-------Dalot
and we just live with Raphinha on Lisandro a fair amount and have Dalot tucking in to help Varane with Lewandowski.
That's a tough team to play against and Barca won't sit back and park the bus so you still get space for Rashford to try to get in behind.
2nd half, Weghorst off for Sancho as a #10 or Antony as a RW (with Bruno playing as a #10) as the game gets stretched, or Sancho on the left, Rashford up top proper and Bruno on the right.