They're hoping an X-ray, which was taken back in Jupiter, Fla., gives them some peace of mind.
It evidently went well, as Stanton said on his Twitter account @Giancarlo27_ later: "All is good, Ready to go! No worries my people."
For now, the team is calling the slugger's injury a bruised wrist, and Stanton will not travel to Fort Myers on Monday when the Marlins face the Red Sox.
"I thought it was broken the first time I saw it," Marlins manager Ozzie Guillen said. "The sound sounded like something broke. You just hold your breath and hope nothing is wrong. Hopefully he is fine. He was supposed to make the trip tomorrow. He's not playing."
The injury occurred in the third inning of the Marlins' 4-2 win over the Mets, in a game called after five innings due to rain.
In wet and windy conditions at Digital Domain Park, Stanton stepped in with the bases loaded. The Mets had just replaced left-handed starter Johan Santana with right-hander Chris Schwinden.
Schwinden's pitch ran up and in on Stanton, who absorbed the pitch on his wrist.
Immediately, his wrist and hand locked, and Stanton didn't try to move it as he walked toward first.
"It's not too bad right now, I'd say," said Stanton, who had his wrist taped in orange-colored wrapping. "Initially, it seemed like my hand locked up. We'll see tomorrow."
Stanton was moving his wrist freely in the clubhouse, but still was experiencing some numbness.
From the sound of the impact, Guillen knew his cleanup hitter was in pain.
Before Stanton reached first base, Guillen and trainer Sean Cunningham ran out to meet him. Without much conversation, Stanton was replaced by pinch-runner Kyle Jensen.
"It's a scary moment, especially with the spot that he got hit," Guillen said. "Players get hit in different places. That spot is very sensitive -- very dangerous and sensitive."
Stanton is 2-for-9 in four Grapefruit League games, and being hit by the pitch with the bases full on Sunday provided his lone RBI of his spring thus far.
Stanton's first reaction was anger. He was aware the Mets were coming up and in on him, even with the bases full.
"I was more [ticked] off," he said. "My hand kind of locked. I was not going to try to move it."
A year ago, Stanton was struck nine times by pitches. He's been plunked in the hand and fingers.
"Those aren't fun," he said.