San Francisco Giants rookie Bryce Eldridge made Major League Baseball history on Wednesday, completing a stunning comeback against the Washington Nationals that hasn't been seen in 17 years.

In a dramatic bottom of the ninth with the bases loaded and the Giants trailing 10-7, Eldridge faced a 2-0 slider from Nationals lefty Mitchell Parker. He connected, sending a 326-foot shot over the right field wall at Oracle Park for a grand slam, sealing an 11-10 victory for the Giants.

Eldridge's achievement is historically significant; he became the youngest MLB player ever to hit a walk-off grand slam, breaking a record held by Hall of Famer Roberto Clemente. At 21 years, 233 days, Eldridge surpassed Clemente, who was 21 years, 342 days old when he hit a walk-off inside-the-park grand slam in 1956.

This grand slam capped an incredible comeback by the Giants, who trailed 9-1 entering the bottom of the eighth. The Nationals had dominated the game and held a 99.9% chance of winning, but the Giants scored five runs in the eighth and completed the improbable win in the ninth.

The loss was significant for the Nationals, who entered the game tied for the third wild card spot in the NL. This defeat puts them a game back of the Padres, who also achieved a comeback win on the same day.

For the Giants, currently at 28-41, Eldridge's performance has been a bright spot in a struggling season, as he boasts a batting average of .298 through 109 plate appearances.