They will be on opposite sidelines Saturday when Georgia visits Georgia Tech in the final regular-season game for each team.
''It's going to be interesting,'' said Marcus Marshall of Thursday's dinner guest list of in-state rivals. ''Hopefully, there won't be too much smack talk. We don't do too much of that.''
The brothers didn't reveal what teammates were invited.
The younger Marshall, a freshman, leads Georgia Tech (3-8) with 609 yards rushing. He is the starter in the B-back position, lining up like a fullback in the spread-option formation.
Keith Marshall recently announced that Saturday will be his final regular-season game for Georgia (8-3) before entering the NFL draft. He could have taken a medical redshirt year after playing in only three games in 2014 because of a knee injury.
''Basically, I just decided I'm graduating so I'm not coming back,'' said the older Marshall. ''I'm taking the next step in life.''
Keith Marshall has missed the last two games with an ankle injury. He said he hopes to play this week, providing depth behind Sony Michel.
''I know it's going to be a great battle between those two,'' Michel said. ''Keith's brother is pretty good. He's been having some success at Georgia Tech. He's going to have to face a good defense on Saturday. That's going to be rough for him.''
One of the brothers will have the final word in future debates about the college rivalry.
''It's exciting. It'll be fun,'' said Keith Marshall. ''I never got to play against him or compete against him, so it'll be fun. It's for bragging rights.''
Keith Marshall began his career as a co-star with tailback Todd Gurley. The two earned the nickname ''Gurshall'' as Marshall had 759 yards rushing with eight touchdowns as a freshman in 2012.
There will be a section of fans, including family members, from the brothers' hometown of Raleigh, North Carolina, wearing custom T-shirts dedicated to Marcus and Keith.
Marcus said his mother, Denise Marshall, had about 30 shirts made for the game. He said the brothers have taken a low-key approach to their only game as opposing players.
''My family, everybody is real excited to watch and those who can come are really excited to see it, but my brother and I haven't really been going back and forth too much,'' Marcus said.
Marcus said having an older brother as a role model ''helped a lot'' as he launched his college career.
''Obviously, I got to watch him go through the same exact thing a couple years ago,'' he said. ''It was really perfect for me. I had someone to look up to and learn from.''
Keith Marshall's pride in his younger brother showed when he said ''he's a very, very talented kid.''
The family pride will only go so far. Keith Marshall said he won't wear Georgia Tech colors while attending one of his brother's games.
''I told him even when I'm done playing and he's at Tech, I'll never put on a Tech shirt,'' Keith said.
NOTES: Coach Mark Richt had testy responses when asked at his weekly news conference if he thinks his future at Georgia is on the line. Georgia was the preseason pick to win the Southeastern Conference's Eastern Division but lost to Tennessee, Alabama and Florida. ''My focus is beating Georgia Tech right now. That's my answer,'' Richt said before adding he'd end the news conference if asked more questions about his future.