Dunn underwent an MRI on his right elbow Saturday and is likely to return to Cincinnati for further testing, Mark Sheldon of MLB.com reports.
Dunn was held out of the lineup for Saturday's 9-7 win over the Pirates after being removed from Friday's 6-4 victory due to elbow discomfort. The Reds want to conduct further tests before landing on a diagnosis for his injury. Dunn was replaced in center field Saturday by Dane Myers and as the team's leadoff hitter by Elly De La Cruz.