Angel City FC has signed Los Angeles native and defender Gisele Thompson to a three-year plus one-year option contract, the National Women's Soccer League (NWSL) club told ESPN ahead of officially announcing the move Thursday.

Thompson, the younger sister of Angel City forward Alyssa Thompson, inked the contract on Nov. 28, four days before her 18th birthday through the NWSL's under-18 entry mechanism.

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Gisele Thompson received her national letter of intent from Stanford this fall and decided to turn down the collegiate offer to pursue a professional deal. The league's under-18 entry mechanism requires consent of the player and their parent or legal guardian. Angel City was able to place Thompson into a senior roster spot right before she turned 18 and without her entering the draft.

"It feels surreal," Thompson told ESPN. "I could have never imagined going pro at this young age. I've always thought, 'Oh, I'm going to Stanford. I'm going to college.' This was never even a thought in my mind that I would go pro this early, but I'm so excited."

Thompson, a U.S. women's national team prospect, told ESPN her decision to sign before her 18th birthday instead of entering the draft or playing at Stanford weighed heavily on the fact that she could play at home in Los Angeles with her sister, finish her senior year at Harvard-Westlake in Los Angeles and continue to build with Angel City.

Angel City general manager Angela Hucles Mangano explained to ESPN that since Thompson signed in 2023, this year will count as her first year on the contract. As a result, Angel City created the three-year plus one-year option to keep Thompson with the team for the next three years, with 2026 being the option year.

"Given how high Gisele would've been drafted [if she entered], we probably wouldn't have gotten her with our current selections," Hucles Mangano said. "We were very intentional and knew the player that we wanted to guarantee and fortunately, we were able to make it work."

Thompson played for the United States' under-20 and under-17 national teams. At the 2022 Concacaf women's under-17 championship, Thompson won gold with Team USA.

Over 10 years ago, Thompson and her sister, Alyssa, joined Total Futbol Academy of MLS Next, a prominent club in Southern California. After playing on the varsity team at Harvard-Westlake during her freshman and sophomore years, Thompson decided to hang up her high school jersey and focus on club soccer.

Gisele and 19-year-old Alyssa are the youngest players on Angel City's roster. In 2022, the sisters made history as the first high school athletes to sign name, image and likeness contracts with Nike.

The sisters will make history again when they take the pitch for the 2024 NWLS season, becoming the second, and youngest, sister duo on the same team in NWSL history. In 2018, Tori and Maddie Huster became the first pair of sisters to take the pitch for Washington Spirit.

Angel City selected Alyssa Thompson as the first pick in the 2023 NWSL draft, making her the first high schooler drafted in the No.1 spot in league history. At that time, Angel City also pursued signing Gisele Thompson.

"It's been about the same time as when we were trying to get Alyssa to be part of Angel City that we were looking at getting Gisele, too," Hucles Mangano said. "That was really strategically part of our mindset and the ability to have both Alyssa and Gisele started when we were trying to get Alyssa and to secure that No. 1 draft spot.

"The strategy has been over a year in the making for Gisele because even at that time, even though she didn't know which direction she wanted to go, we were hoping that we would get to this point."

While then-17-year-old Gisele Thompson decided against turning professional alongside her sister, she started practicing with Angel City in preseason and continued throughout the 2023 season. During that time, Thompson said, she began to observe her older sister's experience and seriously entertain the idea of going pro.

"This all really started when I was training with Angel City. From Alyssa's point of view, she didn't really know what to expect when she turned pro. I was just seeing what Alyssa's been through and knowing what to expect," Thompson said.

"I love playing with Angel City and being around them. And they treated me like I was part of their family. It felt like I was meant to be there."

Throughout the 2023 season, Alyssa's parents, Mario and Karen Thompson, witnessed their daughter watch from the sideline as her older sister made a name for herself as a professional soccer player.

"I saw that glimmer in her eye," Karen said. "I would ask her, 'Can you see yourself out there?' And without hesitation, she said, 'Yes.' She saw her sister out there handling it, and I think she had the same conviction and feeling that she could be pro and go out there and perform."

When the sisters take the field for the 2024 season, they will play on the same team for the first time in more than two years.

"I can't wait to help her score, assist her goals," Gisele Thompson said.

That excitement is shared by Alyssa Thompson, who helped lead Angel City to its first playoff berth this year and finished her rookie season with four goals and two assists.

"I would not want her anywhere else," she said. "I definitely wouldn't want to play against her. She's going to bring a level of tenacity on the field. We both trust each other in our respective positions and know that we have each other's backs.

"We hold each other to a really high standard, and we trust the other person enough to get the job done."

Hucles Mangano told ESPN that Gisele Thompson will have the "opportunity to develop" with Angel City.

"This is not a situation where we're putting any additional pressure or asking her to shock and change the world or change the game ... She has time to develop," Hucles Mangano said. "She has time to come into her own as a professional athlete. And the reason she was signed is because she is good at this age."

She added: "Gisele has an element of versatility that hasn't even been explored yet. She has an ability to play more of an attacking mindset from that back line...She fits into our style of play. We want to have exciting players part of Angel City who can be creative. And I think Gisele brings that as well."