"Basically, he will get DL'd," manager Don Mattingly said. "Not official, but we'll have to get somebody for him."
The Marlins' depth is being severely tested, because along with Bour, they also expect to place their two primary shortstops -- JT Riddle and Miguel Rojas -- on the DL. Both are dealing with left shoulder issues.
Candidates to be called up to replace the three are infielders Christian Colon, Mike Aviles and Tomas Telis. All three are at Triple-A New Orleans.
Tyler Moore, who started at first base, is the likely candidate to get much of the action in place of Bour. Catcher J.T. Realmuto is another option to play some first base, especially if Telis is on the roster. Telis is a catcher who also has played first base.
Bour, being used as the designated hitter on Monday, was replaced in the fourth inning after experiencing discomfort.
"Can't really even describe the frustration level," Bour said. "Just took some swings and a little bit sore, then felt something on that last at-bat there on the oblique. [Talked with] the trainers and decided it was best to come out."
In his lone at-bat Monday, Bour bounced into a 6-4-3 double play to end the first inning. He pushed it down the line, and when his turn in the order came up in the third inning, Ichiro Suzuki pinch-hit and remained as the DH.
It's been a rough couple of days, physically, for Bour. The left-handed hitting first baseman fouled a ball off his right foot on Sunday in a 6-3 loss at Cincinnati, and playing in an American League ballpark on Monday provided a chance to use him as the DH.
Bour is batting .289 with 21 home runs and 63 RBIs.
Fantasy spin | Fred Zinkie (@FredZinkieMLB) Batting .289 and on pace for more than 30 homers and 90 RBIs, Bour has been one of the year's top fantasy bargains and should be stashed in virtually every format. Bour's shallow league owners can turn to waivers for a replacement such as Trey Mancini, Josh Bell or Matt Adams, while those in deeper formats can check on the availability of Tommy Joseph, Lucas Duda or Matt Davidson.