Seager at 21 years, 129 days old is the youngest Dodgers starting shortstop since Bobby Valentine, who was 21 years, 110 days old on Aug. 31, 1971.
Jimmy Rollins started the last 18 games at shortstop, including each of the last nine days, so he gets a day off to open the series. Seager will likely see time at third base in this series as well, with Thursday night the fourth straight day with a start for Justin Turner, a mark he has surpassed just once this season.
Seager started 88 games at shortstop for Triple-A Oklahoma City, and 15 more games at third base.
Dating back to 2013, Seager faced off a few times against Colin Rea, starting for the Padres on Thursday night. Seager was 3-for-11 (.273) with a triple, a double and a walk against the right-hander, including 1-for-6 with a triple this season.
Seager will wear No. 5 with the Dodgers.
Andre Ethier is not in the lineup, one night after fouling a ball off his right knee. Scott Van Slyke gets the start in right field.
Matt Kemp has had a rough first season in San Diego, but he has been heating up of late. Over his last 18 games, the old friend is hitting .333/.390/.667 with six home runs, four doubles, a triple and 25 RBI, and he has reached base by hit or walk in each of his last 22 games.
Kemp has just three singles and three walks in 25 career plate appearances against Dodgers starter Mat Latos, hitting .136/.240/.136 against him.