Grimm, 27, has appeared in 46 games for the Cubs this season. He was optioned to Iowa on July 30 to make room for Brian Matusz, who made a spot start. In one relief appearance with the Minor League team on Aug. 1, Grimm struck out three batters in a scoreless ninth inning. Grimm was recalled when Hammel had to tend to a family matter.
• Cubs reliever Hector Rondon was not available Tuesday night because of a sore right triceps. Manager Joe Maddon said the injury was not serious, and they were taking a precautionary approach.
"Nobody in the training room feels there's anything seriously wrong," Maddon said. "They're just being careful now."
Rondon planned on playing catch Wednesday.
"It's not an issue," Rondon said. "I feel a little tired and tight, too. I prefer to do my treatment and see how I feel [Wednesday]. ... As soon as I feel good, I'll be in the game."
• The Cubs and Josh Collmenter have reportedly agreed on a Minor League contract. The team would not confirm. Collmenter was the D-backs' Opening Day starter in 2015, and spent the first six weeks of this season on the disabled list because of tightness in his right shoulder.
Collmenter had appeared in 15 games with Arizona this season, all in relief, giving up 12 earned runs over 22 1/3 innings for a 4.84 ERA. The D-backs released him on Sunday.