PHILADELPHIA -- Instant replay made its debut on Friday night at Citizens Bank Park, when a home run call on a ball hit by the Nationals' Kory Casto was upheld.

With the Phillies leading, 7-3, with two outs in the top of the sixth inning, Casto hit a Joe Blanton pitch over the right-field wall. Phillies manager Charlie Manuel appealed the call to first-base umpire Bob Davidson, questioning whether or not a fan had reached over the wall and touched the ball in the field of play, which would have resulted in a ground-rule double.

However, Phillies right fielder Jayson Werth believed the ball went out of the park for a home run and confirmed it with the fan involved.

"I thought it went out, but I was kind of running. So it wasn't 100 percent [certain]," Werth said. "So, I asked the guy [in right field] if he reached over. I was like, 'Did you reach over?' And he said 'No.'

"I talked to [center fielder Shane Victorino]. He thought it went out, too."

Davidson and fellow umpires Andy Fletcher, Alfonso Marquez and crew chief Mike Reilly discussed the original home run call, then proceeded to a spot adjacent to the third-base dugout, where the TV monitor is located. After a short time, Reilly signaled home run.

"Actually, on the field, we all thought it was a home run," Reilly said. "But Charlie Manuel asked if we'd use replay, and we have the technology in the ballpark now, so we went to the replay and the replay clearly showed that the ball was a home run.

"I don't know how long it took. We saw three different angles on it and all three showed that the ball was in the stands."

Casto acknowledged that it was weird being in the dugout knowing that the home run could be overturned.

"You are kind of sitting there, and it's just the moment where there is a little bit of indecision," Casto said. "You know what's going on. They could reverse it. At that point nobody really knew what had happened."