CINCINNATI (AP) — Cincinnati Reds outfielder Tommy Pham and San Francisco Giants outfielder Joc Pederson were involved in a brief altercation before Friday’s series opener at Great American Ball Park.

While the Giants were warming up in the outfield, Pham confronted Pederson in the outfield during pregame warmups. The pair quickly were separated and no punches were thrown.

The incident was witnessed by reporters and occurred before fans entered the ballpark.

“We’re investigating it and learning as much as we can about the incident,” Giants manager Gabe Kapler said. “We’re taking it very seriously. Until we have a clear understanding of what happened, not willing to discuss it.”