John is not surprised that his parents decided not to attend the game.

“We talked about a lot of different things outside of football,” John said. “It’s not forbidden, but what are we going to talk about? I understand why they do this. It’s great, but it’s hard.”

Both coaches say the focus should be on the players, although sibling rivalry has been the storyline that has gotten the most attention.

“I’m sure he doesn’t want to talk about himself.” Jim said. “I don’t want to talk about myself. It’s what it is. A big game, for sure. Two teams going against each other.”

Ravens backup quarterback Josh Johnson played for Jim at the University of San Diego and says their brothers come from the same DNA.

“They love football,” Johnson said. “They have a father who is a coach and who loves football. They put in the time and work. They are committed to the process of becoming great.”

The Harbaughs strongly support each other and John isn’t surprised to see the Chargers fighting for a playoff spot after finishing 5-12 last season.

“One of the best coaches of this generation,” John said. “Even if he wasn’t my brother, I would say the same thing.”

The Harbaughs will converse on the field before the game while their teams warm up, but once the ball is thrown, they will be engrossed in the competition. Meanwhile, another chapter of football’s most high-profile sibling coaching rivalry will unfold.

“I’m pretty sure it’s going to be some good times before the game,” Johnson said. “During the match, it will be competitive, like they don’t know each other. After the match, everything will probably go back to normal. That’s what I expect.”