Ferdie Pacheco, “the fight doctor,” a boxing presence for four decades as the physician in Muhammad Ali’s corner and later a ringside television analyst, died on Thursday at his home in Miami. He was 89.

His death was confirmed by his wife, Luisita Pacheco.

In the early 1960s, Dr. Pacheco’s love of boxing drew him to the gritty 5th Street Gym in Miami Beach, where Ali, then known as Cassius Clay, was among the young fighters honing their skills under the renowned trainer Angelo Dundee.

Dr. Pacheco joined with Dundee when Ali rose in the pro ranks and remained with Ali during most of his reign as the charismatic heavyweight champion.

He played a last-minute role in the fight that first brought Ali the heavyweight title.

When Ali’s “wild-eyed” behavior, as Dr. Pacheco put it, caused Ali’s blood pressure to soar at the weigh-in for his February 1964 fight in Miami Beach with Sonny Liston, the boxing commission’s doctor, who took the reading, asked Dr. Pacheco to examine Ali away from the circus atmosphere. Finally calm, Ali told Dr. Pacheco that he had acted “crazy” to scare the famously intimidating Liston, and when the doctor took his blood pressure it was normal.