NEW YORK — For the first time this season, the Celtics’ starting lineup was interrupted as guard Derrick White missed Saturday’s game against the Nets due to personal reasons. It’s believed to be because of the birth of his second child.

Celtics coach Joe Mazzulla said he didn’t know yet if White would be available for Boston’s next game on Monday night at Minnesota. Al Horford took White’s place in the starting lineup against the Nets.

Almost unbelievably, Saturday marked just the second time White has missed a game since he was traded to the Celtics in February 2022, and both times have been because of the birth of his children. The last time White missed a game was Game 2 of the 2022 Eastern Conference Finals against the Heat because of the birth of his first child. He played all 82 regular season and 20 playoff games for the Celtics last season.

Mazzulla doesn’t take White’s availability for granted.

“Like most of our guys, we can just count on him,” Mazzulla said. “They’re always available, they want to play, they love competing. So when you have guys you can rely, it just makes it easy to prepare.” …

Mazzulla coached Saturday’s game with sunglasses on due to an irritation in one of his eyes. He said it is unrelated to the eye injury he suffered during a pickup game last season. … Nets guard Ben Simmons was out Saturday due to injury maintenance.