DETROIT – Erik Spoelstra blamed himself for a “horrendous mistake” after calling a timeout Tuesday night that the Miami Heat didn’t have with 1.1 seconds left in overtime, a technical foul that gave the Detroit Pistons the decisive free throw.

Malik Beasley made it and the Pistons defeated the Heat 123-121 on the opening night of the NBA Cup game.

“I just made a serious mental mistake there at the end,” said Spoelstra. ‘That’s up to me. I feel terrible about it.’

The Heat held a 121-119 lead after Tyler Herro’s basket with 1.8 seconds left. But after a timeout, the Pistons made a well-executed inbound play, with Cade Cunningham throwing a lob pass that Jalen Duren knocked down.

Spoelstra quickly and angrily stormed onto the field and called for a timeout.

“There’s really no excuse for that,” Spoelstra said. “I’m 17 years old now. We had talked about it in the conversation, I knew we had nothing. I just got emotional and reactive about that and I just made a terrible mistake there at the end. It’s a shame.”

Spoelstra has won two NBA championships, was an assistant coach on the U.S. team that won an Olympic gold medal this summer, and was the overwhelming choice of executives responding in the NBA.com GM Survey as the NBA’s best coach, who 69% earned. the mood.

But he made a rookie mistake Tuesday that canceled out a brilliant performance by Herro, who scored 40 points, including 10 3-pointers.

“You don’t want it to come down to a mental mistake like that,” Spoelstra said before a long silence. “Yes, you would have liked this to go into double overtime. That’s the kind of game it looked like. It deserved to go into double OT and not have anyone get in the way of that, and unfortunately even if I experienced coach in the way.”