There was a time when the last thing Ryan Tierney wanted was to be coached by his father, Seth.

Both recall the incident, which occurred when Ryan was 10 years old and had just lost a lacrosse youth league game at Massapequa’s Field of Dreams. “I made a mistake,” Hofstra men’s lacrosse coach Seth Tierney said. “He was too young and I was coaching him like a college kid. We’re driving home and I’m saying, ‘Why’d you do this? Why’d you do that?’ He had a normal kid’s reaction at that age. He said, ‘I quit.’ ”Ryan remembers his father, “trying to take over the game. He tried to over-coach us in overtime. I missed a shot. I didn’t like that my dad was the coach. I didn’t like having all that pressure on me. When I was younger, I didn’t love the game the way I do now.”

Ryan didn’t quit. Seth did.

“I knew I was wrong. I told him, ‘I’ll just be your Dad.’ He went back at it and worked at it. I became an assistant on his club team. I was the ‘good job’ coach. A kid could’ve thrown the ball into the parking lot and I’d be saying ‘good job.’ ”

That wasn’t Ryan. He has been throwing the ball to open teammates and into nets in summer leagues and on high school fields ever since. The Massapequa senior is a nationally ranked player who could have been a national recruit. Except for one tiny detail. Ryan wanted to be coached by his father at the next level, a decision that produced another memorable Tierney family moment in the summer of 2014.

“One night he came into our bedroom. He sat at the end of the bed and said, ‘I want to commit to Hofstra. I want to play for you and I want to do this thing together,’ ” Seth recalled. “I know the coach’s hat and the Dad’s hat will get spun around a few times, but it made me feel good. My wife, Maureen, started to cry.”

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Ryan said he went through the recruiting process, at his father’s insistence, even considering playing for his father’s uncle, Bill Tierney, the iconic former Princeton coach who guided Denver to its first national championship last year. “But it didn’t feel right. Hofstra’s always been home,” he said of his father’s school since 2006. “The decision was easy. And my mom will get to my games, too. That’s a big thing for me.”

But before Ryan plays for his father, he has one more year to play for Tim Radomski at Massapequa, a serious contender for county, Long Island and state titles in Class A, a hat trick the Chiefs achieved in Ryan’s sophomore season when he scored 47 points playing on the first midfield.

“It’s like having another coach on the field,” said Radomski, who will rotate Tierney between attack and midfield. “Ryan tells us things and sees things we might have missed.”

Ryan scored 67 points last year with 36 goals, and for his career has 68 goals and 65 assists, a testament to his team-first mentality. Having bulked up to 185 pounds, the 5-10 lefty is primed for an even better senior year. “His skills are off the charts and he’s very unselfish. He’d rather get the assists than the goals,” Radomski said. “Besides being a finisher, he draws double-teams and still manages to find open guys. He makes things happen that make you shake your head.”

Which made Seth Tierney very happy.

“I couldn’t see myself playing against my Dad,” Ryan said.

There was a time when he couldn’t play for him, either.