Griffin is starting at shortstop and batting seventh in his major-league debut Friday against the Orioles.
Pittsburgh officially added the 19-year-old to the big-league roster earlier Friday, and he'll slot into the bottom third of the order in his first game with the major-league club. Griffin has just five games under his belt at the Triple-A level but has a .950 OPS overall during his minor-league career. The top prospect is also expected to finalize a nine-year, $140 million contract extension in the near future.