Not a big fan of starting Auba and/or Pepe here, but I think there's a decent argument for it.
Red Bull Frankfurt (or whatever this team is called) is our toughest opponent on paper and a good result here would mean it's more likely we finish top of the group, and I think the draw for the knockout rounds is going to be tough this year with some mean teams dropping down from the Champions League group play.
We arguably put too much emphasis on Europa League last year, but taking it too lightly would be equally stupid at this stage of the season. We don't know yet what our league campaign is going to look like. EL could still end up being our best bet to get back into Champions League.