"I probably should have said something, but [I] really just wanted to get through that inning on a positive note," Kelley said. "It got really tight [Saturday] morning. Not 100 percent what it is, but I can't throw right now."
Kelley missed nine games earlier this season with a lower back strain. In 22 appearances this year, Kelley is 3-2 with four saves and one hold.
"It's unfortunate, but things happen and you have to deal with them, I guess," Kelley said. "It's not ideal."
This marks Cole's second stint with the Nationals this year. He threw six innings of one-run ball in a win against the Phillies on May 6. In Triple-A this season, Cole is 3-2 with a 5.68 ERA in 10 starts.
Chris Bumbaca is a reporter for MLB.com based out of New York and covered the Nationals on Sunday. This story was not subject to the approval of Major League Baseball or its clubs.