"I'm kind of going to let it sit for a few days," Rodriguez said. "It's his ball, let him enjoy it, and then go from there."
All Rodriguez can do now is wait. Yankees media relations director Jason Zillo said that the team offered Kowalczyk various types of autographs and memorabilia from the clubhouse, but the lucky fan has neither accepted nor declined the proposals.
"He didn't say no," Zillo said. "He said, 'I need to sleep on this.'"
The marked ball -- No. 10 from the specially-labeled cache used in Rodriguz's at-bats leading up to his 500th homer -- was verified and authenticated after Kowalczyk was moved to a private box for the remainder of the game. Kowalczyk left the stadium with the ball in his possession, without speaking with Rodriguez.
"It's his ball," Rodriguez said. "The thing is, obviously, I would love to have the ball. We'll see what happens."
Although Rodriguez didn't leave on Saturday with the milestone-marking ball, he packed up just about everything else. Rodriguez's helmet from the at-bat will be sent to the Hall of Fame in Cooperstown, N.Y., but the All-Star third baseman kept the home run-hitting bat, the lineup card signed by all the umpires, and his uniform from the game.
"Not even washed," Rodriguez said. "I just took it home."
If Rodriguez does add the No. 500 ball to his memorabilia collection, it will join balls from his first home run, his 40th long ball from his first 40 steal-40 homer season, and home run No. 300.
The ball from homer No. 300 was much easier to attain than the No. 500 ball is proving to be, as an Angels fan angrily threw it back onto the field at Angel Stadium on April 2, 2003. Rodriguez ran out and picked the ball up off the field, waving a thank you toward the right-field crowd.
"I was so excited about it," Rodriguez said. "I was a young pup back then, and it was really cool. It was right-center in Anaheim, and the guy really chucked it back into the infield."
Rodriguez said after Saturday's game that he would like the ball from home run No. 500 to help commemorate the event for his two-year-old daughter, Natasha, who was not at Yankee Stadium to witness the shot in person. If he cannot get the ball from Kowalczyk, though, the stadium video will be the next best thing.
"We have the film, and it's something I'll get to share with her," Rodriguez said. "It was a pretty cool moment."