Both sides in this Carabao Cup tie have lost the player who usually joins the lines, and I think that matters more than the fact that both will rotate. Chelsea are without the suspended Cole Palmer and Joao Pedro, with a young keeper in goal; Liverpool are waiting on Wirtz's ankle and still unsure about Szoboszlai. So I'd ask who loses less when the link player disappears: a Chelsea front that has to be rebuilt around Emegha, or a Liverpool midfield that is being rebuilt behind Isak.
Chelsea first. Per Goal's preview, Palmer is suspended after the red card against Tottenham, and BBC Sport (via AOL) quotes Alonso saying Joao Pedro is out for a few weeks. Alonso's own line, per Liverpool's team-news page, is that Chelsea must find the balance between their attackers' strengths and how they connect. Emegha is back from his hamstring problem and could make his debut, and Estêvão and Welbeck are available. Penders is expected in goal after his own goal on his first league start.
Liverpool's side. Iraola has said he will make changes but still wants to win. Our recent list has Liverpool playing every three or four days (Villarreal, Brighton), and Isak, per the Evening Standard, has six league goals in seven appearances and is expected to lead the line. Araújo and Kerkez are each one booking from a ban, which is a small reason to watch how aggressively they defend.
What I'd look for is the first twenty minutes: whether Chelsea's new front players get the ball in positions to link up, or whether Liverpool's patched midfield lets them. I'm not sure either way, and it's a cup tie with rotation, so the XI could change the picture.