Spurs’ Romeo Langford owes Celtics manager Joe Mazzulla

Like many first-round draft picks, Spurs guard Romeo Langford arrived in the NBA in the summer of 2019 to set the league on fire.

He had been one of the nation’s top recruits, graduating from New Albany (Ind.) High a year earlier, a McDonald’s All-American, Indiana State Mr. Basketball, and every blue-blooded college basketball was coveted program in the country.

Langford had no doubt what skills put him on every coach’s must-recruit list.

“I was a goalscorer first,” Langford said.

After a college season in Indiana, Langford was drafted by Boston 14th overall. He came up with visions of 30-point games dancing in his head.

It was a relatively unknown Celtics assistant named Joe Mazzulla who first hit Langford with the unfortunate news.

If Langford was looking for playing time, in Boston or anywhere else, he was looking at the wrong end of the field.

“He told me, and I’ve kind of seen it ever since,” Langford said, “the way I’m going to play in the beginning is defense.”

The Celtics visited the AT&T Center on Saturday for the first time since the trade last February, which brought Langford — along with veteran guard Josh Richardson and a 2022 first-round pick — to San Antonio in exchange for Derrick White.

Langford is stepping in as Spurs’ shooting guard and Devin Vassell will have knee surgery next week.

Mazzulla is Boston’s head coach and handed the reins to one of the Eastern Conference’s top teams in September after the team suspended scandal-plagued Ime Udoka for the season.

Count Langford is one of the unsurprised Celtics who made it to the NBA Finals last season and kept running despite the coaching change.

Under the 34-year-old Mazzulla, Boston came to San Antonio with a 27-12 record, best in the East.

“Joe has wanted to be a head coach for a while,” Langford said. “He’s been waiting all this time, and now he has the opportunity.”

Langford will never forget his early days working alongside Mazzulla in Boston.

The two worked to refine Langford’s jump shot, work that is still ongoing. They spent more time sharpening Langford’s defenses.

“He was the one who got me into it,” said Langford, 22. “I’d say 60 percent (of the time) was defense, working on close-outs, angles, how you take certain steps when you’re getting hit. ”

Spurs manager Gregg Popovich has been happy with what Langford has given the team in its pinch this season.

“He’s a pretty good defender,” Popovich said. “He knows how to play. He’s feeling more and more confident as the minutes go by.”

It was an important season for Langford, who came into Saturday averaging 6.9 points in 24 appearances, including 11 starts.

His contract expires at the end of the season, making him an unrestricted free agent.

Whatever Langford achieves, wherever he ends up, he’s sure to send a thank-you card to Mazzulla in Boston.

“I love this guy,” Langford said. “I probably wouldn’t be here without him.”

Vassell is aiming to return in February

Spurs have not offered a definitive timetable for Vassell’s return after he went under the knife in New York on Wednesday.

Popovich said surgery to Vassell’s troubled left knee, which has kept him out of eight games this season, is unlikely to end the guard’s third-year campaign.