David Diosa could not have picked a better time than to score his first goal of the season. (Photo courtesy of the Cosmos)

UNIONDALE, N.Y. — David Diosa’s legacy is New York Cosmos history already was secure.

As a member of the Cosmos’ U.S. Soccer Development Academy Under-18 team in 2010, he scored the first goal in a competitive match since the club’s reboot.

On Saturday night, he accomplished something that should rival that, connecting for the first goal in the Cosmos’ 2-0 win over ASC San Diego that propelled the side into the National Premier Soccer League championship game.

“It was a big deal,” Diosa said. “Actually, the team was pretty complicated, a pretty good team. We were having a little trouble on the offensive side. We were having a little trouble finishing. So, that’s what we needed, a first goal for ourselves to open up the game more and score the other one.”

The Cosmos will host defending NPSL champion Miami FC in the final at Mitchel Athletic Complex in Uniondale, N.Y. on Saturday at 7 p.m.

Diosa hadn’t started in the two previous playoff games.

“I’m always ready,” he said. “I’ve got to stay ready when I have to start for when I’m on the bench. Today, the coach decided for me to start. I was happy about it because its something you want to do every time you’re going to play.”

The 26-year-old Diosa, who has been a part of three Cosmos championship sides in the North American Soccer League since 2013, hasn’t started much this season, but head coach Carlos Mendes saw something in training that made him decide to put him in the Starting XI.

“He’s been training excellent,” Mendes said. “He has stepped into games, whether he’s started some or coming into games. He has improved throughout the year. So, he’s a fantastic player. He has pro experience playing at a high level. We felt he would fit a good role tonight. He obviously was a key player for us. Very proud. Happy with his work.”

The Queens, N.Y. resident showed how well he fit into that role in the 53rd minute as he latched onto a Ricardo Bocanegra pass, burst by defenders and scored to give the Cosmos a 1-0 lead.

His reaction?

“Pure happiness,” he said. “It was about time to have a special game for me to score. The whole season, when I’ve played, I think I have been playing well, trying to score. I missed opportunities. Today was like recompense. It was just great for me, a great feeling after what I went through last season, it was a lot of happiness for me and my family. The injuries I had last year. I couldn’t really play. Only the people that were close to me knew what I went through. This was big for me.”

Last year Diosa signed with the Real Monarchs in the United Soccer League but injuries kept him sidelined for most of the season.

“He’s very clever, puts himself in good spots,” Mendes said. “We felt coming from wide and making those runs, he would be effective, and he was. Great first goal in terms of the build-up. Playing through that line in-between defenders, that makes it difficult to mark and when you have a clever player like him.”

Diosa also played a big role in Junior Burgos’ penalty kick in the 76th minute as he was fouled on the right side of the box.

And about that 2010 goal, which was scored against South Central Premier (Connecticut).

“It was really important at that time,” Diosa said. “Many people knew the story with the Cosmos, but I think knew we had such a great team and what it meant to all of us, what it meant to the office for the Cosmos to be back. It was a really important goal. For me to be the first one, it was a great feeling for me and my family.”

If Diosa and the Cosmos win the NPSL championship on Saturday, it will be another great feeling for him and his family.