Yasiel Puig struck out in the ninth inning of Sunday's 7-5 win and then did not return to right field in the bottom half of the inning. Before the game, Mattingly told reporters that Puig "grabs something every time he takes a swing and misses."
Asked what injury caused Puig to leave Sunday's game, Mattingly said, "I guess his back." He then seemed to react sarcastically when asked about the severity of the injury.
"Shoulder yesterday, back today, so I'm not sure if they're going to get him tests or get him to the MRI Monday or a bone scan on Tuesday, maybe," Mattingly said. "I'm not quite sure what we'll do. We may not do anything. I'm not sure."
Puig, who batted .122 in spring training, busted out of his slump by going 3-for-5 with a double and two RBIs Sunday, but he also made decisions that turned into two ridiculous outs on the bases. Puig dashed for second on his RBI single in the third inning. Dee Gordon was held at third base, and Puig was thrown out easily. When a ball trickled away from catcher Miguel Montero in the sixth, Puig broke for third and was out by 10 feet.
"It was a rough day," Mattingly said.