The Bears emailed 14-year-old Miguel Reyes, from Elkhart, Ind., and let him know he would have two tickets and pregame field passes waiting for him.
"I'm really excited to go," Reyes told ESPN.com on Friday night.
Reyes invited his former teacher Peg Kelly, whom he refers to as Aunt Peg, to attend the game with him. Kelly is an avid Packers fan and the one who asked Reyes to give the tumor a name last year. Playing off the rivalry between the two teams, Reyes named the tumor Aaron Rodgers because, he said, Rodgers always beats the Bears and Reyes wants to win this time.
"He's ecstatic," said Reyes' mom, Christy Reyes. "The first thing he said is, 'My Aunt Peg and I are going to have so much fun down there watching the guys warm up.'"
The head of an Elkhart nonprofit organization arranged for Miguel Reyes and his family to attend the Bears' game in Atlanta last year. Devin Hester, who is Reyes' all-time favorite Bears player and now plays for Atlanta, surprised Reyes by visiting him in his hotel room. The following week, former Bears safety Chris Conte invited Reyes and his family to attend the Bears' game against the Miami Dolphins at Soldier Field.
"When I called [Kelly] and let her know we got two tickets, she said, 'No way, you should go,'" Christy Reyes said. "I said, 'No, I got to experience this last year; this year you're the Packers fan and he's the Bears fan. You're going. You're family.' It's what Miguel wants."
Kelly said she hopes to meet some Packers before the game, although many players are too focused on the game to greet guests.
"This is incredible," Kelly said. "Just to see his face, and for him to see my face will be great.
"My whole life I wanted to meet Brett Favre, and now I get to meet all the Packers and Bears. At least I hope to meet Clay Matthews."
While Miguel Reyes and Kelly will be guests of the Bears, Christy, her husband, and Miguel's uncle and brother will be on hand as guests of the owner of a Chicago car dealership who read Miguel's story.
It has been an emotional week for Reyes, who started his eighth round of chemotherapy Tuesday.
"The chemo on Tuesday makes his whole body hurt," Christy Reyes said. "It kind of settles in his back, and it feels like his back is breaking. Then he takes pain medication, which makes him nauseous.
"But by Tuesday it should be completely through his body, and by game time on Sunday, he should be fired up."
It might take him a while to get entirely fired up, but Miguel Reyes already is looking forward to the game. And he's not discouraged by the Bears being the underdog.
"I have faith in them," he said. "I hope they win, and I really think they will."
One thing that's certain is Kelly will know she's not in Lambeau Field.
"We're sitting on the Bears side," Reyes said. "She's going to be wearing everything Packers, and I'll be wearing everything Bears. Not everyone is going to like her."