Watch: Top Orioles prospect hits grand slam for first career home run in return to majors

Holliday sent an 85 mph slider from Blue Jays relief pitcher Yerry Rodriguez 439 feet to right field.

The slam was Holliday's first career MLB home run. On Tuesday, he was called up for the second time this season from Triple-A Norfolk. The Orioles initially called him up on April 10, but Holliday struggled in his first 10 MLB games.

He had two hits in 34 at-bats (.059 batting average), striking out 18 times.

Holliday, 20, was the first No. 1 pick out of high school since 2017 after a historic career at Stillwater HS. As a high school senior, he had the most hits (89) in a season in prep baseball history while batting .685 with 17 home runs and was named the Gatorade Player of the Year.

He fared much better in the minors early in his pro career, and the extra time in Triple-A this summer might have been the best thing for him.

Holliday has a career .304 minor-league average, including .270 in 91 games at Norfolk the past two years.

His MLB start hasn't been as memorable, but that could change. At the very least, he won't soon forget his first major league home run.