I would quibble with that a bit. I saw the quote. It was in response to a question of whether Sancho COULD start at striker, and he said yes (basically) but then said something about how Zirkzee had just arrived at Carrington and it depends on training. A lot of people are just starting training, though, but I'll go out on a limb and say Bruno is starting even if he took this week off and started training next week. Not that that's the same, but I'm just saying.
I think it will obviously be either Sancho or Zirkzee, but I think it could go either way. I think we'll know a whole lot more after the Community Shield (I would expect Sancho to start there; if he doesn't then this would be pure manager-speak).