I personally think the plan would have been play Kelleher in the group games and then Alisson in the knockouts, but of course he got injured so it's been Kelleher throughout bar the USG game. I completely agreed with that at the start of the season, was obviously nice for Kelleher to get the minutes in very winnable games. Klopp has said loads of times over the past few years 'it's his competition' in regard to both of them (Alisson usually getting everything bar the League Cup, but usually we've been in the Champions League, where he'd obviously still be playing in if we were in it).
Maybe he will keep Kelleher in should we progress, I just don't really see the point of not going back to Alisson even though we can win it with Kelleher. I think if Alisson is fit but he starts Kelleher next Thursday, he'll stay in for the potential semis and final. Any result tomorrow and I think Ali should play the second leg. Win comfortably and he has a nice game to come back and get 90 minutes in. If we win a tight game however, or draw/lose, there's just no benefits to not starting your best keeper, perhaps the best keeper in general. It might be harsh on Kelleher but as long as Alisson is here he'll always be the back up, and he's played close to 30 odd games already this season. Not bad going for a deputy.