Nava became only the fourth player to connect for a slam in his first major league at-bat — and second on the first pitch. Cleveland's Kevin Kouzmanoff did it on Sept. 2, 2006, against Texas, according to STATS LLC.
Nava accomplished the feat in the second inning of Boston's game against the Philadelphia Phillies on Saturday when he sent Joe Blanton's fastball into the Red Sox's bullpen in right field.
The lefty hitting Nava was called up from Triple-A Pawtucket before the game. Outfielder Josh Reddick was optioned back to Pawtucket.
Nava is the 10th player in Red Sox history to homer in his first at-bat, and just the second to hit a slam. Rip Repulski hit a slam on May 10, 1960.