What happened: Ethan Salas ended it with a walk-off hit at 20 years, 110 days old. He became the youngest MLB player with a walk-off hit since Manny Machado reached the mark at 20 years, 69 days on Sept. 13, 2012.

Why it matters: The swing adds another landmark to Salas' opening week in the majors after his first hit on Sept. 14 and his first two home runs on Sept. 17. It also gives San Diego another late-game contribution from a 20-year-old producing immediately in the season's final stretch.

What to watch: The next check is whether Salas keeps landing high-leverage at-bats as the regular season winds down. His recent run has turned each start into another measuring stick.