Hitters also were informed as to what pitches were coming.
Right away, Stanton saw the obvious from Fernandez, ranked seventh on MLB.com's Top 100 Prospect list.
"He's got a little cut to his fastball, which is always good," Stanton said. "For the guys who throw hard, to have movement helps. The speed already separates them. When they have movement, it just puts them in a whole new category."
Fernandez, a 20-year-old who throws in the mid-to-upper 90s, projects to start the season at Double-A Jacksonville. The Marlins have never shied away from promoting players from Double-A to the big leagues, if they show success.
"He will be next to us pretty soon," said Stanton, who made the jump from Double-A to the Marlins at age 20 in 2010.
The towering Stanton is unlike any hitter Fernandez has ever faced.
Asked how many players looked like Stanton in the Florida State League, Fernandez answered "Nobody."
"That guy, he's unreal," Fernandez said. "I've never seen a guy hit the ball as hard as he does. It's just impressive. I saw him hitting balls in batting practice yesterday. He was hitting balls like abnormal."
In their mini-showdown, Stanton mostly took pitches. He did swing and bounce a ground ball to second.
"I compete every time," Fernandez said. "Seeing hitters there pumps me up. I was competing."