Accidents happen. Few people know better than John Leguizamo, who was sparring the other day at the Church Street Boxing Gym in Lower Manhattan with his longtime trainer, Jenaro Diaz.

“Stay loose, keep that shoulder back,” Mr. Diaz urged him, with Mr. Leguizamo making sure all the while to keep his gloves up, shielding what is arguably an actor’s prize asset, his face.

“He wouldn’t hit me there,” said Mr. Leguizamo, 51, as he hopped down from the ring to settle on a cast-iron stair. “But this sport can be as dangerous as you want to go.”

Mr. Leguizamo has courted peril throughout his career. Once while filming, he said, raising his palm to his temple, “I was hit so hard that my head pounded for a week.”