Aaron Murray will play in his 51st game as Georgia’s quarterback when the Bulldogs’ play No. 7 Auburn at Jordan-Hare Stadium on Saturday, and he has a lot of scars to show for it. One in particular stands out more than any other.

There’s a big, round chunk of skin missing just under the left side of Murray’s chin, where the hair of his beard doesn’t even grow anymore. It is courtesy of one Nick Fairley, a former All-American defensive lineman for the Tigers, and it was the result of Fairley grinding his facemask into Murray’s chin after he was on the ground in 2010.

That was Murray’s first personal experience with the Georgia-Auburn rivalry, the Deep South’s oldest, and it shaped his perspective forever.

“I wasn’t really a Georgia boy before I got here,” said Murray, a senior from Tampa, Fla. “So I really didn’t know much about Georgia rivalry games except for the Georgia-Florida game. I never really disliked (Auburn) too much. Then the game came, and after a couple of those hits I was like, ‘OK, I don’t like Auburn anymore.’ Now I understand what it’s all about.”

Murray — the SEC’s all-time leader in passing, touchdown passes and total offense — has fared pretty well in the series. Georgia lost his first meeting to the eventual BCS champion Tigers, but he’s been a big part of winning the past two by a combined score of 83-7.

Yet Murray is not the quarterback everybody is talking about entering Saturday’s game (3:30 p.m., CBS). No, that would be Auburn’s quarterback, Nick Marshall. And understandably so.

Marshall started his career at Georgia, and he wasn’t even a quarterback when he donned the red and black. Marshall signed with the Bulldogs out of Wilcox County High in 2011 as a cornerback. And he would start for Georgia in this game had he not been involved in the dorm-room theft of a teammate. He and two other UGA players were dismissed from the Bulldogs’ program.

But Marshall has resurrected his football career at Auburn, and Auburn has been resurrected, too. After a season in junior college playing his old position, Marshall showed up on The Plains in July, won the starting job and now is considered one of the main reasons for the Tigers’ renaissance under first-year coach Gus Malzahn. Marshall has accounted for 2,035 yards of offense as Auburn rolls in with a 9-1 record (5-1 SEC).

“I’ve said on plenty of occasions, if a guy has a situation where he doesn’t finish at Georgia, a guy that signed with us, my goal for him is to find a new home and have success there,” Georgia coach Mark Richt said this week. “So I’m happy for Nick.”

Now, No. 25 Georgia (6-3, 4-2) has the unenviable task of trying to stop Marshall and Malzahn’s maddening zone-read offense. Few teams have had much luck in that regard. The Tigers rank first in the SEC and third nationally in rushing yards, at 320 per game, and they have averaged 38.6 points. Tre Mason, Marshall’s primary partner in the quarterback-running back exchange, has run for 1,038 yards and an SEC-best 16 touchdowns.

But if the Bulldogs’ defense does anything well — and that hasn’t been a lot this season — it’s stop the run. While they’ve encountered nothing the likes of which they’ll see Saturday, they’re fourth in the SEC and 20th nationally in rush defense 126 yards per game.

“That’s what our front seven does, we stop the run,” said junior linebacker Ramik Wilson, who leads the SEC with 92 tackles. “We like the matchup.”

The added wrinkle to the whole affair is the players charged with corralling Marshall are the ones with whom he was the closest at Georgia. But the Bulldogs’ defenders seem genuinely excited about the challenge.

“We’re real good friends, but I’m really looking forward to the matchup,” said junior cornerback Damian Swann, who roomed with Marshall in UGA’s Reed Hall. “It comes with the business. Guys leaves schools and go to other places all the time. We did it with (Zach) Mettenberger a month ago. We’re going to step it up and play hard.

Somewhat lost in the Marshall storyline is how very meaningful Saturday’s contest is to the SEC championship race. A win Saturday and next week against Kentucky coupled with losses by Missouri in its final two games will put Georgia in. Likewise, Auburn could represent the West with a win over the Bulldogs and one against No. 1 Alabama when the Iron Bowl renews in two weeks.

But clearly both teams are focused only the matchup that will unfold Saturday — and that’s plenty enough.

“It’s an intense game,” Murray said. “It’s right up there with the Georgia-Georgia Techs, the Georgia-Floridas, us vs. South Carolina. Obviously this one means a lot.”