Challis was diagnosed with an adult form of liver cancer in 2006, but after receiving a grim outlook by the doctors, he has beaten the odds thus far.
A resident of Freedom, Pa., Challis first met the Yankees during their recent trip to Pittsburgh. He said he will keep his allegiance with the Pirates, but Challis wanted to see Yankee Stadium in its final year, and on Tuesday he got his wish.
After a tour of Rodriguez's apartment in New York City, the two drove to the stadium and Challis saw the Yankees' clubhouse, the dugout and got a tour of Monument Park.
The recent high school graduate stood behind the batting cage while Rodriguez and the rest of the Bombers took batting practice. He even took a nap in manager Joe Girardi's office.
And while there's no question the experience was a memorable one for Challis, Rodriguez said it's something he will never forget either.
"The treat's for me to be around him," A-Rod said. "He has a great attitude. It just reminds us of how fortunate [we are] and all the blessings that we have."
Challis wore a Yankees jersey with Rodriguez's No. 13 on the back as he answered reporters' questions before Tuesday's game against the Rangers. His story has captured national attention, and he started the Courage for Life Foundation to provide sporting experiences for high school athletes with life-threatening illnesses.
And even standing next to one of the biggest names in Major League Baseball, Challis simply felt happy that he could get his message across.
"If I was able to make one person realize how anything can be taken away in one swift swipe, then, sort of, my word got spread," Challis said. "That makes me feel good."
Samantha Newman is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.