Immediately after, Belt tucked the ball in his back pocket before joining his teammates in mobbing Cain on the mound.
"I had thought about that before the last out," Belt said. "I just wanted to give Matt the game ball so I put it in my pocket so it wouldn't fall out. I didn't want someone stepping on it and rolling an ankle."
Belt gave the ball to Cain when the celebrations wound down in the clubhouse.
"I asked for a Corvette but he said he wouldn't give me one," Belt said.
Many of the game's souvenirs, including Cain's hat and glove, were sent to the Hall of Fame, while Cain got to hold on to the game ball.
"He was trying to keep it and put it on eBay," Cain said with a smile. "That's Brandon for you."
Belt said he had never been more nervous on a baseball field than at the end of Cain's historic outing, but he was more than excited to be part of it, especially the last out.
"That was pretty cool. It's hard to explain," Belt said, adding that he had watched the replay of the last out at least 15 times. "You watch that stuff on TV, and you think about how you're going to feel for your teammate. Honestly, it was one of the best feelings. It was pretty cool. Seeing how excited he was after the game was just awesome, and I'm glad I could get him the ball."