I assume that Erik ten Hag's first choice would be Rashford again instead of Ronaldo. Actually it might depend on Ronaldo's performance against Sheriff Tiraspol. Most probably we would see him in the starting eleven again and he needs to use this chance well. I wouldn't expect to talk about Ronaldo like this but his job isn't easy while Rashford is making such a big effort.
But overall, Leeds have decent stats, and if you leave out that big loss to Brentford, Leeds looks like a tough nut to crack. According to the result of the game with Socedad, it is clear that United is far from being a clear favorite in games with the middle peasants, so it's hard to predict something here. I think in the game with Sheriff both forwards will get time to prove themselves and if Ronaldo does not show something special, then he will again be released as a substitute.