During a Showtime boxing broadcast in February, one of the network’s analysts, Raul Marquez, praised a Houston welterweight as a “tough guy” who had sparred with his son Giovanni, a promising amateur.

On Friday night, Marquez, wearing a bright blue blazer and a white-patterned dress shirt, called the latest Showtime event from ringside in Deadwood, S.D. — about 20 minutes after he had worked the corner in Giovanni’s professional debut.

“I’m back now!” the elder Marquez, a former junior middleweight world champion, told his fellow announcers after changing out of the black T-shirt and black sweatpants he had worn during his son’s fight. When asked who was the more nervous between the two of them, he laughed and said: “Are you kidding me? I was more nervous.”

There is a short list of retired professional athletes, like Floyd Mayweather Sr. and Doc Rivers, who have coached their children as professionals in the same sport. Some retired pros who have transitioned to broadcasting, like Bob Griese, have called pro games involving their children.

But while a handful of boxing analysts who are also trainers, like Teddy Atlas of ESPN, have juggled both jobs on the same night, Friday night’s event chained several accomplishments together: Marquez coached his son’s professional debut and then changed wardrobes to cover the rest of the card live — the plan all along, win, lose, or draw.

Giovanni Marquez’s welterweight fight was all the more notable because Showtime’s “ShoBox: The Next Generation” program typically features fighters with far more seasoning. So given Showtime’s avid promotion of the event, Raul Marquez said he could understand why some boxing fans might have been skeptical.

“If you want to say my name helped him get this opportunity on Friday, then that’s fair,” he said in a video interview along with his son last week after Giovanni’s last prefight workout at the Raul Marquez Boxing Fitness Gym in Humble, Texas, outside Houston.

Then again, Giovanni Marquez, 21, has been generating boxing buzz for some time. At the National Golden Gloves championships last year in Tulsa, Okla., he won the 152-pound title and was voted the outstanding boxer of the tournament. His amateur record was a gaudy 75-12.

“Gio has been dealing with the perception that his success is the result of his dad’s name his whole life,” said Raul Marquez, 50. “But he never complains. He puts his head down and works, and the results speak for themselves. My name didn’t help him dominate the amateurs.”

Giovanni Marquez added that he did not feel much pressure as a result of bearing the family name.

“I just have faith in God,” he said. “Work hard. Stay focused.”

The younger Marquez’s opponent, Nelson Morales, had his own compelling story. He was born in the Dominican Republic, grew up in Newark, lives in Scranton, Pa., and is a part-time police officer who trains whenever he can. Morales, 30, entered the bout with a 2-0 professional record, he said in an interview on Tuesday, just as he had finished getting a haircut.

“I’m just trying to look good on TV,” he said. “I’ve got to sell myself.”

With a wife and two children, and a third child on the way, Morales said he relished the chance to fight the son of a world champion.

“He’s got a great team, he has a lot of potential, and he will have another opportunity,” Morales said. “I’m not going to have another opportunity in 10 years.”

He added that his stepfather, a longtime boxing fan, revered Raul Marquez. “After I beat his son, I would still love an autograph, to give to my dad,” he said.

Boxing has long been a Marquez family endeavor. Raul Marquez, who was born in northeastern Mexico and grew up mostly in Houston, started boxing when he was 7, trained by his father. He was one of three Mexican Americans on the 1992 U.S. Olympic boxing team, a group that also included his roommate in Barcelona, Oscar De La Hoya.

Marquez, known as El Diamante, won the junior middleweight, or 154-pound, title in 1997 and retired in 2008. He then became one of the few broadcasters of color on English-language boxing broadcasts in the United States. He also does Spanish-language work.

His oldest sons, Raul Jr., 29, and Arturo, 25, were accomplished amateurs. Arturo, in fact, signed with the boxing promoter Bob Arum and Top Rank and won his first 10 professional fights before an eye injury ended his career.

Giovanni Marquez may be the most promising. After participating in sports like swimming, soccer and football, he focused on boxing as a teenager, trained mostly by his grandfather. Unlike his father, an aggressive southpaw, Giovanni Marquez, who is right-handed, said he was comfortable boxing inside or at distance and occasionally switched stances, going from righty to lefty, to confuse opponents.

Outside boxing, he recently finished his associate degree at Lone Star College and plans to transfer to the University of Houston to study finance.

“I don’t look at it like a Plan B,” he said. “I want to be successful in boxing and in business things as well.”

Before the fight, Raul Marquez said he understood that anything could happen, especially as his son was for the first time not wearing boxing headgear.

“We’re hoping everything goes well, but you have to have an open mind if it doesn’t go well,” he said. “I’m sure it’ll affect me, but I have to do my job.”

The four-round fight took place at the Deadwood Mountain Grand Hotel.

Giovanni Marquez is just the seventh boxer to make his debut on “ShoBox.” Among the others are the undefeated welterweight Errol Spence Jr., one of the best pound-for-pound boxers in the world, and Gary Russell Jr., who had held the WBC featherweight title for seven years before losing in January.

At 5 feet 9 inches and 143 pounds, Marquez was shorter than Morales by an inch and lighter by a pound and a quarter, while giving up three inches of reach. After a tentative first round, Marquez gained more confidence and became more aggressive, with his uppercut particularly effective.

Between rounds, Raul Marquez, working as a trainer, offered his son pointers while urging him to breathe.

“Relax,” he said. “Take your time. Take your time. More jabs.”

Giovanni Marquez won by unanimous decision.

“This is what we live for, ” he told reporters afterward. “I come from a fighting family, and I’m looking to continue the legacy. I’m grateful.”

After about 20 minutes, Raul Marquez returned to the ring, in his business attire, alongside the announcers Barry Tompkins and Brian Campbell. He had missed the fight after Giovanni’s — a second-round knockout — but provided detailed analysis for the main event, in which Ardreal Holmes defeated Vernon Brown in a tough 10-round middleweight bout.

As Raul Marquez commentated, his victorious son returned to the arena. Beaming, he took photos with fans and then sat with his brothers and his mother to watch the rest of the action and soak up the rest of the night.

Gabriella Angotti-Jones contributed reporting from Deadwood, S.D.