Alex Muyl has a new No. 1 fan: Sophia Behrens, a three-year-old pediatric cancer patient who helped design boots with the New York Red Bulls midfielder this summer.

The Red Bulls partnered with Tackle Kids Cancer, which raises funds for research and programs at the Children’s Cancer Institute at Hackensack Meridian Health, to work with pediatric cancer patients to help sketch out the custom boots. The Red Bulls wore the boots during warmups to show support and raise awareness for the cause.

When Sophia came to visit Muyl at Red Bulls Training Facility to design the cleats he would wear, she had just gotten out of the hospital and was exhausted from treatments.

"Alex tried to talk to her and to make her stay awake the whole time but after a while, she just gave up and she just fell asleep," Sophia's mother, Wendy, said. "Once she got up from her nap, she was like, 'Where’s Alex? Where did Alex go?' And we were like, 'He had to go to practice.'"

Alex Muyl will be wearing these boots, featuring Sophia's name in bright colors and some of her scribbles#TackleKidsCancer | #RBNY pic.twitter.com/SCrNwPH2xv — New York Red Bulls (@NewYorkRedBulls) September 20, 2018

The Red Bulls invited Sophia and her mother to stick around and watch training.

"The whole time we stayed out there she was like, 'Come on Alex! Go Alex!'" Wendy said.

Sophia eventually became too tired to stay and they had to leave training, but they've been to Red Bull Arena since for home matches to cheer on Muyl.

"He’s so genuine, Alex, even from the moment that we met him he was just really kind and sweet towards her," Wendy said. "He didn’t look to her as the cancer patient, he just saw her as Sophia, the little girl."

Since the first meeting, the two have started an incredible friendship, that is helping both "Fifi" and Muyl.

"Sometimes you’re meant to meet people," Wendy said. "It’s funny because his birthday is September 30 and September 30 is the day that she got diagnosed."

The two have been intertwined beyond a date on the calendar, especially after Sophia gifted Muyl a t-shirt with her face on it for his birthday.

Sophia told her mother: "Let’s get him the shirt that has me on it, holding myself."

Since then, Muyl has worn the shirt for every home game.

"He wears me now," Sophia said.

During that same time, the team is undefeated at home and hasn’t given up a goal since then.

"It’s been lucky for me and also just a reminder," Muyl said. "There are bigger battles to be fought and it’s very humbling for me. I feel lucky to be in her life."

When @Alexmuyl19 and “FiFi” designed their boots together for @TackleKidsCancr, they became fast friends! She came out to the match again today — and brought Alex a present for his birthday: A shirt with her face on it!!! #RBNY pic.twitter.com/MWefs96cHs — New York Red Bulls (@NewYorkRedBulls) September 30, 2018

Sophia watches Red Bulls games on TV and asks her mother to point out where Muyl is on the field.

"We show her and she’s like, 'Come on Alex! Come on! You can do it, you can do it!" her mother said.

Aside from the shirt, Muyl and Sophia each have one cleat from the pair of boots they designed together.

"I have one at my house and she has one," Muyl said. "That program was amazing and I’m so happy that she was able to come into my life like that."

Most of the time, fans of a club get a shirt with their favorite player on the back. For Muyl, he gets to wear his "number one fan" on the front of his shirt.

"I’m just in love with her," Muyl said. "I adore her. She’s great. Love you, Fifi!"