The team said that X-rays at the hospital were negative and the Cubs' orthopedic surgeon will evaluate him on Tuesday.
According to a source, Capps was experiencing stiffness and soreness in the elbow, the Pittsburgh Post-Gazette reported.
With the Pirates up 10-8 and one out in the bottom of the ninth, Cubs catcher Geovany Soto hit a screaming shot straight back at Capps. The right-hander turned his body, but the ball struck his elbow and then ricocheted off the field between home plate and third base.
The line drive hit Capps hard enough that according to a team source, the seam marks it left behind were still visible after the X-rays were taken, the Post-Gazette reported.
Capps grimaced and immediately started to walk toward the dugout and was met by Pirates personnel.
The 25-year-old right-hander experienced some numbness and tingling after being hit. Although Capps said his range of motion was better by the end of the game, the team's medical staff still sent him to the hospital.
Sean Burnett came on in relief, got the last two outs and earned his first major league save.
The injury cast a pall over Freddy Sanchez's big night. The Pirates' second baseman went 6-for-6 in the win.
Information from The Associated Press was used in this report.