BOSTON -- Not all of David Ortiz's home runs are created equal. The 507th of his career, in the eighth inning Friday night, was extra special, but not for the reason you might think.

Yes, Ortiz's two-run shot into the seats atop the Green Monster at Fenway Park provided the winning margin in the Boston Red Sox's 4-2 victory over the archrival New York Yankees in the first meeting between the teams this season. More significant, it fulfilled a promise that the iconic Sox slugger made before the game to a 5-year-old fan who is coping with tetralogy of Fallot, a serious congenital heart defect.

As Ortiz tells it, former Red Sox teammate Kevin Millar told him about Maverick Schutte. Millar and Ortiz filmed a video before Friday night's game that Millar sent to Maverick's parents in which Ortiz said, "You take care, buddy. And I'm going to hit a home run for you tonight. Remember that. For you."

Sure enough, Ortiz belted a first-pitch curveball from Dellin Betances, his first hit in eight career at-bats against the dominant Yankees reliever.

After the game, Millar visited Ortiz in the Red Sox's clubhouse and showed him a message sent by Maverick's parents. In a 23-second video, Maverick said, "Big Papi, you never let me down, and you're the best player ever in the Red Sox game. And I'm trying the hardest to get out there at Fenway Park and meet you. Great homer! We saw it."

"Millar came to me and Millar was crying and he was showing me the video that Maverick sent," Ortiz said. "It was very touching, and I started thinking about it right after. When I got home, that was really when I was like, 'Wow. I can't believe this really happened.' Millar told me that his parents haven't seen him that happy in a long time. He has been very sick. I always say that there's something special out there. I'm a huge believer in that."

It wasn't the first time Ortiz had come through on a vow to a young fan. He said he met a sick girl at Massachusetts General Hospital a few years ago, promised her he would hit a home run, and delivered later that night.

Several years ago, Ortiz, who says he's "crazy about kids, especially a sick kid," formed the David Ortiz Children's Fund, which partners with Mass. General to raise money to help pediatric cancer patients throughout New England and the Dominican Republic.

"Listen, it's not a guarantee. This is baseball," Ortiz said of his home run promises. "This is not, 'Hey, I'm going to shoot a free throw when nobody is playing defense on you, or I'm Stephen Curry and I'm going to hit a 3-pointer.' Stephen Curry can shoot a 3-pointer and you know it's going to happen, regardless. This is baseball.

"But what you're trying to do, that video, what I was trying to do was make Maverick feel happy and have that connection with him. You throw that [about hitting a home run] out there just to make sure he has a friend he can count on right here. But then it happens.

"While the game is going on, I'm not thinking about it, to be honest with you. I can get away with it because I'm a power hitter, and if I put a good swing on the ball, it can possibly happen. Everybody understands it's not that easy. But then when it happens, a situation like that, me, personally, I'm a huge believer of God. I believe He had a lot to do with this. I saw the video [Maverick] sent back, and he got all the stuff on and you saw how happy he was. That's something that touches you."