49ers vs. Raiders: 5 Niners who must start 2023 preseason hot

QB Trey Lance/Sam Darnold

We'll start off with an obvious one and that's the continual battle for the backup spot behind starting quarterback Brock Purdy, who you wouldn't expect to play at all given both his cemented status as the 49ers' starter (Shanahan hasn't, to my memory, ever played his assumed starter in the preseason) and the fact that he's coming off an injury.

But the 49ers will need quarterbacks to play on Sunday, and while the joint practices will likely give Shanahan and quarterback coach Brian Griese more insight into how the competition between Trey Lance and Sam Darnold is going, I'd expect each of them to get some playing time in the game on Sunday.

How much time remains to be seen, but I wouldn't be terribly surprised if each got a quarter in the first half, followed by Brandon Allen taking over to finish the second half.

That said, it will be imperative for each to show what he can do, given that neither will have the benefit of throwing to first-team receivers or standing behind the first-choice offensive line.

Sure, that will limit what can really be gleamed about either Lance or Darnold, but Shanahan will more concerned with their processing of the offense than the outcome of certain plays.

What each does against the Raiders won't be the only litmus test of the weekend, but if one quarterback shows a great deal more than the other, it may suggest that one could be rising to the top of this particular battle.