If Kris Bryant, Addison Russell, Ben Zobrist and Anthony Rizzo are voted in as starters, it would be just the second time in baseball history that four infielders from the same team started the game.
The Marlins are looking for pitching and have held preliminary talks about trading for Jake Odorizzi of the Rays and Drew Pomeranz of the Padres, according to a source.
Andrew Lambo, who has played for the Athletics after being claimed off waivers from the Pirates, is recovering after undergoing surgery last week for testicular cancer.
Stephen Strasburg was scratched from Monday night's start against Clayton Kershaw and the Dodgers, but the Nationals don't believe his upper-back strain is serious.
The Cubs have created a plan to use a three-catcher rotation with Miguel Montero catching Jake Arrieta, David Ross catching Jon Lester and Willson Contreras possibly catching the teams other starters.