While I don't think any of the four can cause serious issues, as a person who intended to see del Potro in person tomorrow, Serra is easily the least interesting option. Rosol would bring some energy to the crowd, given the curiosity of Wimbledon; it'd also be a fascinating ball striking exhibition. Berankis is a player I've always been intrigued by due to size and scrappy style. I have no clue who Bautista-Agut is - I'm guessing a claycourter living off challengers but he did win 2 HC qualifying matches. Serra is a player who never interested me, has been the luckiest SOB this Grand Slam season and his game makes Delpo not have to do much.
I'm sure you'll still enjoy it. Still, a bit unfortunate for you that Nalby withdrew, would have been awesome to watch Delpo vs Nalby out.
This will be a one-sided rout, but you'll get to watch JMDP's awesome forehand live, that's always a great sight.
Serra in 3: 7-6 7-6 6-0.
You're clearly overrating Del Potro. No way will this one dimensional ballbasher get 12 games against a much superior all-court talent like Serra, just no way